What Causes Painful And Frequent Urination Post Intercourse?

I just recently got off my period I think maybe on 3-9-15, well last night (3-12-15) my boyfriend and I had sexual intercourse. I was fine when I used the bathroom afterwards. All day today 3-13-15 I have been peeing nonstop and it has a bad pain when I hold it for longer than 30 seconds. I can pee and it s kind of painful at first but mid flow I m alright then as soon as I m done the pains back a little but it stops after like 45 seconds when I wipe (been doing this all day) I have a very light light blood color and it is worrying me. I can sit on the toilet and just rest there until the pain stops and when I got up I could see faint blood like I found on the toilet paper in the toilet bowl. Also I can urinate and sit on the toilet for a minute or 2 or 3 and I pee again same problems.