What Causes Constipation?

I am a 45 year old women, hard bowl movements and been drinking plenty of water over the past 3 weeks, last week i was having pain and discomfort in the stomach, at the time i had watery loose stools, took admoidium A.d. for 2 days to try to stop the Discomfort, after drinking any milk or meat products my stomach would cramp up and I would have adominal Discomfort and Hard Stools, difficulity passing, to almost a sweats after trying to push stool out. Sunday, at the Er all Afternoon, took exrays and put iv fluid in , could not find anything in the ex-rays, this has been continuing on for four years now and symptoms keep reacourring., I was thinking it has something to do with a colon Blockage, i have not ever had a colonoscopy done, I still have female problems with my hormones issues since 2006 and its been getting worse , is it time for hysterectomy, my mother, is passed on now, she had hers out at age 42, my sister had hers out at the age of 34.