Frustrated over prolonged stomach cramps

Hi, I usually have stomach cramps after menstrual period. I am cold all the time and need to put on extra cloths. Sometimes, my symptoms are followed with diarrhea. And I heard it is normal to have faster bowel movements in period and to be more sensitive to outer influences as well. A friend of mine, suggested I might be pregnant, but home pregnancy test showed negative. Some women respond to menstruation in a way that they barely move because of the pain, I guess that in time you will learn more about your body and how to deal with pain.