Hi OP, I agree with the above posters. I suffer massively with health anxiety that started after I had my first dd who is now 4. I had pain in a raised lymph node I have, and then found a lump in my breast and spent her first Christmas in tears waiting for a referral, thankfully no issues with my lymph node and other turned out to be only a fatty lump. Since then I've had counselling which did help, and I've also been on sertraline which was great, however I came off it in July because I felt better, then 4 weeks ago I had heart flutters for a few seconds and since then I'm worried of dropping down with a heart attack. My GP put me back on sertraline last Friday.
I try to rationalise; when I have a bad flare up and I'm laid in bed with it I typically feel really hot, lightheaded, can feel my heartbeat in my ears, sweaty, chest pains, back pain, head pain, shortness of breath.. the list goes on. I rationalise by knowing that these are the signs of anxiety and I'm making myself worse by worrying, so try to distract myself (at the minute I have a word search app I use). Right now as I type this I'm trying not to let my mind wander but I do understand that it's so hard, so you have my total sympathy OP.
I had horrid back pain 2 years ago that came out of nowhere and lasted around 5 months, physio was amazing and sorted it and an MRI found I had two protruding disks, likely brought on by lifting both DDs out of the bath, in and out of the car etc.
If you feel your GP isn't listening, see if there is another you can see. You matter and you deserve to feel 'well' and like 'you' again