Monthly yeast infections, please help!

26 F, 5'6" 118lbs, mixed Asian white

Problem has been persistent for several months on and off. I have found that almost every time I have sex with my SO, I will experience intense burning and itchiness. It will persist long after sex has ended, for several days. This doesn't happen every time, maybe just 70%of the time. I have been to my family doctor a couple times, but she just suggests i take yeast infection meds which doesn't help that much, and it inevitably comes back. I've tried switching out soaps, our detergent hasn't changed for years, i don't use any special creams etc down there.

The burning is inside the labia, no smells, no unusual discharge. Just pain and burning.

Could i be allergic to my so? Please help i can't stand this anymore!!!