I had that not so long ago. It's sort of ranged from swelling and tenderness around the vaginal area, to pain when I pee. One day it was so painful I was almost in tears, and I just took anything I thought might make it go away!!!! Took a sachet of cystitis relief stuff, drank lots of water and cranberry juice. Also had a glass of water with a teaspoonful of baking soda in, cos I heard this helps lower the acidity level of the urine. It was gone within a couple of days. It sounds like what you have is similar to what I had. I think it was cystitis (urinary tract infection) so try the things I tried.
Cystitis is common in women who are sexually active and happens because the urethra (in females) is only about 3 centimetres long. So when you're having sex, if there is any bacteria whatsoever in that area (on you or him) it can get pushed up the urethra into the bladder causing infection. If you want to prevent it happening, make sure you are both clean before intercourse, and pee straight after sex as this flushes any bacteria out.
As for the pain and irritation around the vagina, I think this is just from lots of sex!! If you are not very lubricated, or his penis catches you at the wrong angle this can occur.
