condom allergy or worse????

So I am very sexually active, and it's with the same guy except for another guy that's a once in a while thing you know. Anyway, in the last 2 weeks or so, I've noticed when my partner puts it in, the back entrance to my vagina closer to the other side hurts so bad as in stinging. It only happens for a second and I get used to it and barely any pain, but I'm worried about what it is because I used to get the pain when I was with my ex, and it stopped and now it's starting again. I did however get a yeast infection about 4 weeks ago and used monistat and had a reaction to the stuff and I was swollen and bleeding, and the same day I went to the dr for that was the same day I got the shot birth control. So I'm spotting a lot too now, also after sex, I bleed just a little as if I have a cut or something.... can anyone relate or can someone tell me what they know, I need help! DX