Slight pain in right abdomen.

1.When I sit down on my chair for many hours during day for office work,I feel slight pain in my right abdomen when bending down/forward.The pain is not continuous and only occurs during bending. I don't have any visible lump in my abdomen. Also I feel slight pain in back while stretching if I spend many hours sitting on chair.My chair has high back and ergonomically designed but I have a habit of sometimes half-sitting without taking back support while focusing on laptop. 2.When I sit down on my chair  for sometime for office work, I easily get stool once a day. But on a holiday,when I spend most time lying on bed or walking/jogging I don't get stool easily even once a day. I used to workout/gym regularly some months ago but I have stopped working out in last few months except walking/jogging. What can be the possible problem/disease?