Hello! Thanks for putting your query in HCM. I am a Gastroenterologist (DM). Cholestyramine resins are used if there is diarrhoea caused by bile acids, as this agent binds the bile acids. So I will like to advise you to stop cholestyramine and instead use high fibre diet along with psyllium fibres and take plenty of fluids. If not relieved with constipation even after this may use some stimulant laxative like sodium picosulphate. Sharp pain in gall bladder area could not be explained from what all you hve mentioned here. I think for that you should get an Ultrasound abdomen of hepatobilliary system. I hope I have answered your query and this will help you. Remain in touch and get-well soon.