Pain in buttock hip & thigh that sometimes goes down front of leg what could cause this . hurts more on sitting down or standing long periods of time.

Low back pain: It's probably starting in your low back. Usually these things resolve within 4 weeks if you are careful, rest, and don't re-injure yourself. Can happen with minimal "injury" like forceful cough, catching a falling object, etc. Do some gentle stretches (forward bends from the waist), use heat or ice for comfort. Consider physical therapy if no better. See a Dr for weakness or bowel/bladder changes.