Welcome to the forums. I'm so sorry to hear that you're struggling with these health issues, and I'm certain that Covid-19 hasn't exactly made things easier on you.
You've hit upon one of the tricky parts of health anxiety, and indeed anxiety in general: it can cause tons and tons of physical symptoms, but also our bodies are complicated and that means lots of other, non-psychological things can cause them too.
I have to stress that I am not a medical professional, and certainly don't have any special insight into your condition specifically. However, I think it is worth mentioning that statistically, it is much more likely someone with pre-existing anxiety and OCD's wide range of symptoms are indeed anxiety-based, and not a rare or dangerous illness that fails to show up on a number of medical tests.
All this to say that, yes, everything you mentioned are symptoms I myself have experienced from anxiety. But that's not to say that what you're feeling is real, or "all in your head." Even "real" symptoms are all in our heads, and to the person experiencing them whether they come from anxiety or some other pathology doesn't change how scary and unpleasant they are!
Luckily we are in a country with quite good healthcare that does not need to be rationed out so conservatively, and I believe you will be able to get just about any test you care to have. MRIs can be expensive and stressful, but I understand why the idea of getting a "clean" bill of health from an actual image is so comforting. Just bear in mind that if anxiety is the underlying problem, it is unlikely that you will find a single piece of medical evidence that you find convincing enough to stop your worrying. For that, you will need a different kind of intervention in the form of lots of hard work and therapy.
Please feel free to keep us up to date on how you go, and to chat a bit more.