Thanks for your update. I would be encouraged overall by your doctor's opinion. Sometimes ruling out can be a discouragement if you still don't know what is the cause of something, but in this case I would be relieved since he doesn't suspect anything more serious.Update:
Been to a neurologist at the hospital. Explained everything I've experienced in the last 4 months. He asked a lot of questions and performed a physical exam.
He thinks it's a temporary issue where my nerves are over sensitive. Small nerves sending out pain signals to my brain for no reason after having the high stress/anxiety period after my surgery. He says he thinks this could be due to changes in stress hormones.
I asked him if we shouldn't do any test, just to see if there's at least nothing blocked in my back since after a run I have pain in the left side in the middle of my back for 2-3 days. He said that was probably because I laid down for weeks/months after my surgery and didn't train my muscles/joints (which is true but still, I used to run 120km a week). He said I should see a physiotherapist or osteopath if this problem keeps on lingering.
His consensus was that he believes it's nothing serious like an immune or muscle disease.
Anyone know what I could do in order to recover if what he says is true and my nerves are over sensitive? It seemed like he said only time would heal.
I'm not sure on your question, maybe check with some similar threads on the forum regarding neurotransmitters, stress response/hormones. How is your sleep quality? Is your caffeine intake high?