Sometimes when my boyfriend first enters me during intercourse, i feel a sharp pain in my lower abdomen. what could be causing this?

See a doctor: Pain during intercourse can have several causes. You might have an infection, which can cause pain during intercourse. There are other causes but you'll need to see a doctor and have an exam to determine the cause. Sexually transmitted infections can often have minimal symptoms in women, so you don't want to ignore this symptom. Good luck.