Burning pain during/after sex

Every time I've had sex with my boyfriend in the past two weeks I can't last that long because my vagina  starts burning and hurting like crazy. I just started this month on the pill, we don't use condoms and haven't in the six months we have been togethe I don't know what's causing this... Has anyone else experienced this? I don't think it's a yeast infection because it doesn't hurt all the time, just during and after sex.  I still get wet, so it's not that.