Oh, I know what you mean OP.
I had something odd a few years back requiring emergency surgery and eicne then I have been like this too about everything.
I have actually got shingles atm and being treated, but apparently can be due to stress and worrying!
I have got this Benenden health now whcih is only about ten pounds a month, but this is a mixed blessing as it gives you access to tests etc.
I already had an ultrasound and MRI with this recently, nothing untoward was found. It was however stressful having the tests / waiting for results etc.
The problem is you can never be sure, there is always some test or scan they haven't done.
With me, I had this rib pain which I know now what the shingles starting but I was convinced it was either an embolism in the lung or lung cancer.
Thankfully as the antivirals work and the pain is going away I am slightly more reassured.
I would hesitate before telling the GP about it, just in case they do take any symptoms less seriously. That may just be me and my anxiety though.