This gets a bit gross lol, so if you're squeamish, please look away

I'm 10 years post-op (Dr. Brassard). No problems in 10 years: no infections, dialation still goes fine, no pain, no issues.
Except...
Five months ago I woke up one day to my vaginal area burning intensely. Seemed mostly outside, both around and under the vaginal opening and the labia folds at times too. It was constant, although the intensity varied throughout the days.
Guessing a UTI, my doctor started me on an antibiotic, and otherwise had me use zinc oxide and hydrocortisone creams on the outer skin just in case it was irritated. After 5-7 days, the burning went away. The UTI culture came back questionable, so I can't say for sure that was the issue.
Skip ahead five months, and three weeks(!) ago the burning returned. UTI tests came back negative, so my doctor started me using the zinc oxide and hydrocortisone creams on the outside.
The pain persisted for a week, so I saw both my Gyno and an ER doctor. Both did internal exams and saw what they assumed was the "obvious cottage cheese" of a yeast infection and started me on Fluconazole (pill) and Monistat cream.
The burning pain persisted. After many more days, the cultures they took surprisingly came back negative for yeast.
So today, three weeks after this started (and still burning), I saw the Physician's Assistant to a TS surgeon who specializes in TS post-op care. She did an internal exam and saw the white stuff inside. It was a clump of *something* that had accumulated around a small patch of hair that had grown inside (potential downside to the one-step procedure). She removed the white stuff, mentioning that it and the whole area has an odor, douched with betadine, and treated what she said was minor granulation at the site with silver nitrate.
She also did her best to remove the gobs of zinc oxide I had been slathering on everything outside for weeks.
My question is: has anyone experienced burning down there for reasons other than yeast infection? Does any of this sound familiar?After three weeks of pain I'm getting a bit desperate to escape it. So far everyone seems to be making educated guesses, but nothing has helped. I do think we're on the right track though, as I noticed a faint odor about the time this all started, so I'm thinking it's all related.
I should add that I'm celibate, so it's not an STD, herpes unlikely, etc. Blood tests normal, EKG normal, the TS Assistant said everything down there otherwise looks healthy and intact, as did the ER doctor and my PCP. I dialate with the largest dilator (blue?) every 4 weeks or so without problems.