I Have Constipation For Three To Four Days Befor I

I have constipation for three to four days befor I go laxatives do no help I get severe pains right side across from belly area and nauseated alot when I do go it may be one bowel movement than nothing than the next time it is as if I was prepping for a colonoscopy what could it be I weigh 101 eat good when I have an appetite