I am 20 years old and I have had my period since I was eleven years old. I have never expierenced cramping or anything. Recently I have got my period every two weeks or less time than that. It has been so heavy that I'm going through several pair of pants and the blood is so thick like some type of clots. Its so painful that it hurts to eat and to walk. I am not on any type of birth conrtol. What do you think this can be?