Small white bump?!

So I've noticed that I get a very small white bump towards the inside of my vagina once me and my boyfriend have had a lot of sex. My boyfriend and I have A LOT of sex and he is definitely above average size.. I went to my doctor about it and it isn't an infection or std. She said it may be from irritation from having too much sex. It dissappears once I haven't had sex in a few days.. was wondering if this happens to anyone else? Or if it's happened before? Helppp