Abdominal pain and digestive problems.

i always had digestive probs, but over the past year the pain in my lower abdomin after eating has gotten bad enough for me to stop eating and i like food. my wait is down to 100 pnds if im lucky. if i eat i swell up like a balloon and severe pain follows, it last until the next morning when i vomit my undigested food. if i dont eat for at least 24 hrs my pain lets up but im to tired to do anything. any one have a clue on what could cause this