My Mom 88 Years Old Has Neuroendocrine Tumors Removed 3

My Mom 88 years old has neuroendocrine tumors removed 3 years ago (carcinoid cancer) She currently wears an ostomy bag ( 3 years). She is experiencing distention of the abdomen and very foul gas in the bag, along with some discomfort to the left side of the ileostomy. Two days ago she had diarehhia . Could this be that the cancer has progressed or something else.
The Dr did a KUB today only saying that there was some distension and if it continues to see a gastrologist.
Any help would be appreciated.