While ejaculating inside my girlfriends vagina, the tip of my penis burned. Is this because she had sex only hours prior to me with someone else using a spermicidal condom? We are extremely active, this is the only occasion in two years when this has happened. Also, the likely 5-10 occasions we had sex following the occasion I experienced the burning, I felt absolutely no such sensation. Attempting to conceive is obviously a factor here. Now, can someone give me an honest opinion as to whether or not what I suppose is correct? thank you