Once again I'm scared for my online friend

So back in July, I made a post expressing worry for my Croatian friend while he was on vacation. He was gone for a week and I was terrified something might have happened. Now, thankfully he was okay then... But now he's disappeared again, and this time I don't even know why.

So, the last time I talked to him was on Friday. We were going about our business as usual until he abruptly stopped replying. The next day, his sister uses his account to inform me that he was gonna be taking a break for a day or two because he needed to unwind a bit. Now, that was on Saturday. It is now Tuesday. And he hasn't said a single word. I've been desperately trying to get his attention, but he just isn't replying, and I am absolutely melting with anxiety, I'm so scared that something bad happened, I'm terrified he might have died or something, there's no way I'd ever know if he did die, I don't want him to die, I'm so scared, I just want to know if he's okay, I just need him to tell me he's alive and well, I'm so scared I feel like I'm gonna throw up, the stress has me crying my eyes out, I hate this so much...