Have no great experience with skin doctors but did go to Martha Fang (
https://www.marthafang.com/) for a long term skin irritant. After giving me some fairly expensive creams I didn't need we got down to the liquid nitrogen which was cheap and mildly painful. It did some good but basically after several treatments I asked if it was simply old age? To which she agreed.
It seems to me that unless you have something bleedingly obvious like as a broken leg or large tumors popping up on your ass most medical situations are still, after all these hundreds of years, open to interpretation. I mean if your foot swells up it could be because you stepped in a hole while you were shit-faced, snake bite or gout.
Dr. House is the best diagnostician so just watch a couple of seasons - hell, it's usually Lupus. Go with Lupus. It's probably Lupus, or gout.