I keep feeling like i'm going to die, what can help?

I'm 18, have no history of complications or mental issues and I've always felt perfectly healthy. But roughly around the start of this year I keep having a sinking feeling of impending death. Not, "somebody's going to kill me!" kind of paranoid, but I'm going to have a stroke or a seizure, or a blood vessel will burst. Anything that can happen inside the body and kill you without having time to do anything about it. I get all fuzzy when i start spiraling into those thoughts.

The most recent spiral was only two hours ago. My mom blew out a candle and my brother immediately got a headache. He put his hand on his forehead and I don't know why that triggered it for me. At first I was scared he was going to have a stroke and the next (ridiculous) thought in my head was I was going to have one in response. I don't think that would happen but when I get like that I don't think rationally. I started feeling like I was out of my body and got all hot and tingly, which as you could guess only added fuel to the fire. I'm great at not showing when I feel like shit so they didn't notice but I'm seriously thinking about asking for help. I don't even know what would come of that or how my mom would react. I already feel crazy I don't need people thinking I am, but I'm so tired of feeling terrified.

In the past couple of years I vividly remember having two out of body experiences, I don't really know how to explain it well. Like I wasn't really there but I was and I felt high for a couple of minutes. It happened on a Christmas morning for the first one, and the next one happened when my head was resting in my girlfriend's lap. Completely different situations and it was the same feeling. No idea why. When I think about it when I'm spiraling I'm convinced they were warnings or something to go see a doctor. I'm so scared of it happening again I felt so helpless.

Can someone explain or have tips on how to stop the spiral? I can't keep doing this it's exhausting and I'm not educated enough on mental/physical stuff. I get too scared to look anything up in case it triggers another one, sorry if this was the wrong place to post this in I have no clue on where to go.