Burping Rotten Eggs and Throwing up?

Have been having this problem for a month or longer. It doesnt matter what i eat my stomach starts hurting very badly, i want to poop and it doesnt happen, it's almost like food is rotting in my stomach. Then i end up barfing up rotten nastiness then eventually i have liquid poop. i'm goin to the doctor today but really think they won't help because i went to the emergency room a week or two ago at 4 in the morning and they didnt do anything for me. i feel like dying!! just want to know if anyone knows what this could be