What Causes Severe Pain And Burning While Urinating After An Intercourse?

Following intercourse and my spouse ejaculating inside me, I have started having severe burning and pain while urinating . It continuesorse for days , even to the point where my vaginal area peels. The pain is sharp and at times wakes me while sleeping . Bearing down to start urinating is also painful. This has happened 3 times in the last few months but not every time after sex. Also I've noticed it happens right before I begin my menstrual cycle. Help