I am sorry to hear you are struggling with these debilitating symptoms. Some of these may be triggered by medications, so I suggest you carefully review your meds with your doctors to see if any of these are an issue. Another thing which cannot be ignored is the mind-body connection. If you have a variant of irritable bowel syndrome
can cause changes in bowel habits. I seems unlikely that this would be related to your surgery. If you are not happy with answers you are getting, you might seek a second opinion
as sometimes a fresh perspective might provide additional answers and options.