Pain during penetration may be associated with a range of factors.. This is often the result of not enough foreplay. Insufficient lubrication is also commonly caused by a drop in estrogen levels after menopause, after childbirth or during breast-feeding. Certain medications are known to inhibit desire or arousal, which can decrease lubrication and make sex painful. These include antidepressants, high blood pressure medications, sedatives, antihistamines and certain birth control pills...Consult nearest gynecologists they will do the needful.