What causes the pain between the groan and navel. the pain gets worse when he stretches his legs or when hes bending. ?

Groin pain: If pain is worse with leg stretching and bending, then this is likely muscular strain from the physical activity or exercise that might have caused it. I suggest he try rest, warm compresses in the area that hurts and anti-inflammatory medications like ibuprofen or naproxen for a few days to see if that relieves it. Take that type of medication with food to avoid stomach irritation