请教各位朋友，我长期腹胀，腹部压痛，还常有想大便的感觉，该查的都查了，连CT都做了，没有查出问题。我该怎么办?

I have similiar situation like you with gas and bloating. I have seen American doctors many times with no help at all. I personally found taking soluble fiber supplement such as Fibercon or Citrucel is helpful for constipation.
Here are some of trouble food for me:
1. fiber in whole grain food, raw vegetable, some fruit, and beans.
2. Fructose intolerance.
3. Lactose intolenrace: milk, cheese, dairy.
3. Can not digest too much fat.

Here is web site that might be helpful. http://www.helpforibs.com/footer/

Good luck!