Is it possible for me to be allergic to my boyfriend's sperm? I have sensitive skin & cant use fragmented lotions & stuff because my skin breaks out & just yesterday after my boyfriend & I had sex, he came on my butt and it began to burn & break out as it would if I were to use a fragemented soap or lotion. So is this really a thing? It's either that or my boyfriend has an STD which would be REALLY unfortunate because I'm almost 100% certain that my boyfriend isn't stepping out on me.