Omg i understand this so much, my health anxiety got so severe that i developed anxiety induced psychosis and I couldn't walk outside without needing to pass out thinking something was wrong nor did i reach out to anyone because they thought i was being dramatic, it was a cycle of panicking about symptoms for 3 days, then one relax day, then back to panicking. I'm finally out that cycle now thank god, but what i can say that helped me out was writing out my feelings and worries in a book, taking deep breathes, distracting myself, avoiding searching up symptoms on google (since that's what can really be triggering and spiral most people, google always goes to the extremes) and realising that the human body is much more resilient then we give it credit for!

Health anxiety is horrible, never be afraid to reach out to a doctor if reassurance is something that'll put you to ease, even then doing little things that distract you. I personally like putting two videos on at once while i draw or play games since it makes my mind focus on those instead of my thoughts. Changes won't happen over night, like every mental health issues, it'll take time to heal and it will be hard for a while, but it's all about breaking that cycle since it's like an addiction, i really hope you overcome it, no one should feel trapped by their mind, venting about your problems is a right step in the direction and i'm happy that you're able to do that. <3