I am 19 years old and my weight is 40 kg. Each time my periods are very painful. Last time also the pain was unbearable. I took 3 pain killers on a single day from morning to night but it didn't became low. It feels like the muscles of abdomen are contracting from inside. Also there is more than usual bleeding sometimes. I am unable even to eat properly. The pain in abdomen is accompanied by pain in leg muscles and back portion especially on left side. I feel dizzy and fainting. This all happen severy time. Why is this so?