stomach pain in sitting position

hi, i would like to ask that when im in a sitting position, i get stomach pains however if im laying down or standing up then there is no pain. This started on the 24th May (1 days ago) and ive still got this pain. Ive never had this before and normaly stomach pains last maximum 1hour. The night before it started (saturday) i done shisha/hoodka and had donnar kebab after that. Then the pain started next day. Also i need to go to the toilet so the pain goes away in the sitting position then it starts  again aftert 10mins.

Thank You