I once got progressively sick over about 2 years, and nobody could figure out why.
Finally, I was at the dentist, and the hygienist asked what the doctor was doing about my bad tooth, which was nothing. He hadn't seen it because he was too focused on a tooth he said was cracked, and not paying attention the tooth which had a bad infection under the gum line. It had killed the nerve, so it didn't hurt, it was just pumping toxin into my body.
I got so sick that I once fell asleep at my desk, and a woke in a startle to my assistant standing over me, saying "Oh my God, I thought you were dead."
Once I got the dentist to do his fucking job, and pay attention to my real dental problem, I got the tooth pulled, some antibiotics, and with 48 hours, I felt better than I had in years.
BTW, I still have that "cracked" tooth. There's nothing wrong with it.