What Causes Lower Abdominal Pain And Pain During Intercourse Post Periods?

After having my period and using tampons I usually have sharp pains in my lower abdomen whenever I bend or squat my lower body. I will also have pain during vaginal intercourse and pain whenever I have a bowel movement. These pains only begin to occur the day after my menstrual cycle has finished and I m no longer using tampons. What could be the cause of this?