It is possible that the operation failed and there are adhesions in you stomach. This simply means that your stomach is closed and the food is not able to pass through. What you need is to meet the surgeon who did the original surgery and then tell him whats happening. Then, he will check it out and tell you if you need to be operated again. also, the bowel is sometimes overactive after surgery. Eat mild foods and cold
food that dont irritate the bowel. This will help keep food down.
Hope this helps.