This type of problems are common after child birth. There are 3 types of solutions to this. One , try to indulge in more foreplay , which would in turn help lubricating the vagina more and you won't feel pain. Plus talk to your partner about this as well so he would also help arousing you more with various ways. Second, try to use some lubrication called KY jelly to reduce the friction during the intercourse which in turn would reduce pain. Last , try to do some pelvic floor exercises including tightening and relaxing muscles around the vagina which in turn would give you positive result. If not relieved please see your cyber and get yourself checked for any problem related to stitches.