Not able to work out... need help,frequent stomach troubles?

i have been doing gym for the last 1 year and everything was going fine until about 3 months ago i started having stomach troubles...i had gained about 15 kgs of weight but in the last 3 months i have lost about 7 of those precious kilos:(i just cant digest anything properly...i tried pepto bismol.imodium and even antibiotics..the doctor says their is no infection but then why am i having these problems...i **** about twice and its not solid...and belive me ive been dying for 3 months to get a solid ****.....everything was going great i had made a great physique but now i am skinny again.... or is it because i havent been going to the gym for 3 months and working out again would help solve my problems...please guys helpp....