@sallybally335
How frightening for you, I'm so sorry because it's horrendous to feel like there's something seriously wrong with you.
When you describe other symptoms such as the throat tightening, they are classic anxiety symptoms. Along with shoulder and neck pain, stomach problems, feeling of not breathing properly. The mind is so good and trolling us and kicking off all manner of physical stuff.
Also, you mentioned that the pulse thing was initially happening when you were out, then just before you were leaving the house etc. That sounds like anxiety to me too.
I'm not a doctor but my advice is try the medication. Sertraline is great for anxiety and I find has fewer side effects than some of the others. If it doesn't help, there will be something else you can try.
What's really really hard about anxiety around health is that you end up not really knowing what's a problem or not. You don't trust your own body and symptoms, you feel like medics don't take you seriously because you're anxious and it ends up ruling your life.
I'd hope your surgery are understanding and caring towards you and take you seriously.
Always get checked out if you feel something is wrong but you also need to do some work at home too.
Have you ever had CBT? It can be great for helping give you coping techniques such as diaries, relaxation and mindfulness, reducing checking and monitoring.