my boyfriend and I had sex 2 days ago using a condom and it wasn't the usual Trojan brand we use and immediately after my vagina started to burn. then the next day everything seemed fine and when we had sex after a few minutes my vagina started to burn again and we had to stop because i was in so much pain. i don't know if I'm having an allergic reaction or what but my vagina is slightly swollen, sore and still has a burning sensation.