Scary tripping experience with my friend

So yesterday, me and my friend both took 300ug of acid. My friend had tripped once before and I had tripped 4 times before this. The previous times we tripped were on 200ug tabs. My friend did one 200ug tab his first time and the most recent time I tripped was on 1.5 which is the most i have done. So the most he had done was allegedly 200ug and the most i had done was allegedly ~300ug. This was also more than a couple months ago so our tolerance was completely reset.

The tabs we took yesterday were brand new. I had recently bought them off the dark net from a very reputable vendor and they were 100ug tabs. I tested the tabs and they were real so i wasn't worried that they were fake or anything. Me and my friend are both 18 and going to college in the fall. His parents were gone for a week so yesterday I went to his house and we both took 3 tabs each. Probably the first mistake was not having a trip sitter but I don't know if that would have changed the way he acted. In the beginning, everything was great. We were both getting really nice visuals and it seemed like my friend was enjoying himself. As the trip progressed, it seemed like my friend was slowly losing his mind. We were leaving his house to walk outside but he was stuck in a loop where he wasn't sure if he locked the door when he left so he would constantly go back to his house,lock the door, leave, then go back, lock the door, and so on. Unable to get him out of this loop I just decided to go back in the house with him. Now I don't know exactly when this occurred, but at one moment he came up to me and told me he was having a bad trip. I tried to assure him that everything was fine and I took him to a different room and played some music, but it didn't seem to help him. He eventually started freaking out and yelling at me and shoving me around, yelling at me to make him have a good trip. It was almost as if he was frightened and was desperate for anything to get him into a positive trip. I guess he saw that I was having a good trip and thought that I was the cause of his bad trip and that I was the only one that could make him have a good trip. He was very violent and was constantly hitting me, shoving me, and pulling me around, yelling at me that he was having a bad trip and that I needed to make him have a good trip. I couldn't communicate with him. I would try to talk him about what was going on but I would lose him like 5 seconds into the conversation and he would resume his yelling and violence. I was extremely scared and paranoid that I wouldn't be able to calm him down considering we were only about 4 hours into the trip and it wasn't even close to over. Then he started throwing up. He was so delusional that he didn't even think to throw up into a toilet or trash can. He would just throw up on the floor and continue walking like nothing happened. It was as if he completely lost his mind. It was when this began that I knew I needed to call somebody who was sober fast that could help me out with the situation. I knew he had an older sister who taken shrooms once and knew that he was tripping that day. I was able to ask him what his sisters name was and then I took his phone in order to call his sister. His sister said she would be over in 15 min, so I just tried to handle the situation until then.

While I was waiting, he continued to yell and throw up all over the house. He kept on saying to him self "new environment, new enviroment" and ran to different rooms in the house as if he was desperately trying to change his mindset. He had taken off all his clothes except his boxers and was running around the house. He then repeated "new enviroment" to himself and dashed to the front door in order to go outside. When I saw this I immediately ran to him and pulled him inside before he was able to step outside. He was yelling at me to let go and I tried to explain to him that he has no clothes on and that he cant just go outside but he wasn't listening. I told him to put on some clothes but he refused to and kept freaking out. He ran upstairs to his office and I followed him to keep an eye on him. Again, he was yelling at me " Are you having a good trip? Because i'm having a BAD TIME and YOU need to make me have a good time". While he was yelling this at me he took his printer from his desk and slammed it on the ground. His sister came home and we somehow managed to calm him down. I think having his sister there was what made him come back to his senses. The rest of the night was spent by me and his sister watching over him and cleaning up the house. All the while i'm still tripping on the same exact dose as him. The experience was intense for me as well but there was never a point where I lost control of myself. I always felt completely in control of myself and calm.

The next morning when I was telling him about the trip and everything he did, he told me he didnt remember a thing and the last thing he remembered was himself sitting on the couch and his sister telling him to relax and telling him that everything was going to be ok.

Ultimately, I am just wondering what could have caused this to happen to him. Obviously I can't ask him because he doesn't remember and since I have never experienced a bad trip I don't know what he was going through. As far as the vomit and throw up goes, I think that just his body reacting to the acid. He threw up on the come down of his first trip but he also smoked weed and so we assumed it was either because it was his first trip or it was just the mixing of the two drugs that caused him to throw up. I guess yesterday confirms that he just throws up when on acid because it was his second time and we did not smoke weed. He ate very lightly that day and the only food he ate while on the trip were a few blackberries which I also had. I learned from that experience to always have a trip sitter when taking acid, especially if you're with someone who hasn't done it a lot, and to increase the dosage slightly. He probably should have just taken two tabs that day since we did not really know what the actual dose of the 200ug tabs were. This 3 tab 300ug trip was more intense than my 1.5 tab 300ug trip but I still estimate that those tabs were at least 150ug. He doesn't have any mental illnesses so I don't think its that either and he said his first trip was amazing

I'm posting this here to ask you guys what you think could have caused his bad trip, if it is normal to not remember your trip at all, if it is normal to throw up.