A little concerned

My husband and I had sex this morning (1am) when we were done I was bleeding. I've never bled after sex before. The blood was bright pink in color and was only there until I wiped a couple times then it was gone. We are TTC. Sex hurt for a second when I fully sat up on him (I was on top) other than that nothing. What could this be from? This is my peak fertile day, I'm at a lost as to why I was bleeding