Sensitive? (Possible TMI)

Over the weekend, I went out of town to visit my Mama. So I obviously didn't have sex or any foreplay while I was gone. (Thursday-Saturday) When I got home Sunday, my boyfriend started foreplay which led to sex. We had to stop having sex because I got suddenly uncomfortable and I became super sensitive. This hasn't ever happened before and I have no clue why. Neither one of us have any STDs. I am 29 weeks pregnant and have had a deal of uncomfortability with baby lately. Does anyone know a possible cause of the unusual, vaginal sensitivity??? Do I need to do anything??