I had that problem for a couple months after I had my son. I ever went to the doctor about it just thought it was cause I wasn't fully healed. At first I thought the doctors messed IP on my csection but it's common for a lot of women.
I was okayed by my doctor to continue. We've only have tried twice since it first happened, and we stop as soon as the pain starts. And that's what we are worried about if our baby is okay, we don't want to hurt her.
I would check with your health care provider as this could but something alarming and to make sure everything is ok with you and the baby sweet heart also to make sure it's safe for you to have sex while pregnant! Its not supposed to hurt when having intercourse it doesn't when my husband and I have make love. Hope this helps God bless you and yours!