Swollen abdomen. Stomach like before.

I was a skinny boy... but due to depression ,i had to visit psychiatrist... so i continued his medicines...on 15 march i was with flat abdomen & stomach and flat body... but on 16th march , suddenly my area below chest got bloated or swollen...it was like my abdomen lose grip with my body...i was taking air till stomach , i was feeling air... so i had sonography but nothing was there, everything was ok... after that for almost 1 year, when i used to stand ,my back started paining above hip region... and now when i get stomach full, i cant stand... i cant eat more or something... its not that " pet nikal aaya" .. its in between abdomen... abdomen is clearly visible now... i miss my skinny days with flat stomach... what should i do now??...how to get back flat stomach like before... please tell me my problem