Hi.. Presence of infection can cause the discomfort during sex.. A few girls have a highly sensitive genitalias, sensitive to infection and every sexual activity just increases the infection... May be that is what is happening with you.. Restrict your sexual activity for a few days or may be few weeks.. You can use tampons soaked in vinegar or use boric acid suppositeries which can help treating yeast infection.. Drink plenty of water to avoid urine infection..