Need to know whats going on.

I stoped taking the pill after my Dec period and am trying to have my last child ( already have 3) and since stopping my pills I have had the skin come off the inside of my lips after my period stops at first I thought it was the,antibiotics I was on but now since I not on them it still happens and it Burns like acid when I pee and it touches it where the skin has come off. It lasts for about a week then goes away till the next period then starts all over again. I have told my Dr and he is clueless on what's causing it or how to make it heal faster. I also took my last gardasil shot about the same time I stopped my pills. I don't know if that has anything to do with it or not. I was born with hpv and am a 2 x Breast cancer survivor took chemo and radiation the 1 St time caught it in time the 2nd I didn't need treatments so can any of this cause this to happen? Please help me. Thank you in advance.