Pain still 4 weeks after colon surgery

It depends. I don't know the 'prep' for colon surgery, but I'm willing to be my next pension check that you had to have a whistle-clean colon before the operation. As in, sort of the same prep, at least, as for an endoscopy.

You may only be experiencing bowel gas due to what you have been eating in the past four days or so, but also which flora has taken over in your gut. Not all bacteria get along well with each other, and not all of them will like what you're feeding them. Somewhere there's a happy medium where things tick along nicely.

Have you followed the prescribed protocols for post-surgery when colon resection is involved.? Did those protocols ask you to introduce pro-biotics of a certain kind at some point? Are you actually (cough)..farting? Or is this just bowel gas moving through the descending colon, or transverse colon (running along under your diaphragm)?

As long as you are passing gas, that's thumb-up territory. If it's extremely painful, keeps you up and night...then you should seek assistance from qualified people. But do consider one or both of: change of diet, introduction of pro-biotics, especially if a certain kind were recommended.