Hi, OP.
I had severe health anxiety for years. I was so bad at times I could barely function. I went through a long period of believing I was going to have a heart attack and ended up crawling up the stairs so I didn't exert myself and die.
That followed by left arm pain that lasted months. The GP told me it was psychosomatic pain. It hurt like fuck, but he turned out to be talking sense.
I diagnosed myself with every cancer going and lived my life in terror.
I finally worked really hard in CBT and for a long time it seemed not to help, then suddenly it did. I had to work hard, I have to fight my anxiety often but I got there.
I was very ill with it, it ruined my life for a long while.
Get all the help you need. It can get better, you can stop living with this much fear. You need to get help and work hard.
People telling you to get a grip is not helpful. It's like telling someone with depression to cheer up. HA is often misunderstood and many people see it as an attention seeking thing when the reality is we are genuinely petrified every second of the day that we are seriously unwell. It isn't logical but it feels very real. I was scared all the time. Scared to even walk up the stairs. I couldn't get a grip.
Mine reached its peak when my children lost their dad to cancer. I was so scared I would leave them too and it made me mentally unwell. I am sure some people thought I should have got a grip because someone I cared for just died of cancer and I was actually fine, but the mind doesn't work that way. It's a real belief to us.
Anyway, I am the happiest I have ever been now. There is hope, there is a life without the fear. It's hard work, it's something I will always have to fight against. You can do it too.
OP, if you ever want to chat please feel free to PM me.