Swollen down there, help!!

So lately my vagina has been swelling up after sex and has a burning sensation as well. I tried using lube and although It helps out a lot it doesn't completely fix it.. it's not a good feeling, sometimes he won't finish because it hurts me so bad and I feel terrible. Can someone give me any tips on what to do? Not sure if it has anything to do with it but I am on the pill however, I've been on it for months now and never had this problem this bad.. any info on this can help thanks!