The following information is from the prescribing information for Apriso:
Mesalamine has been associated with an acute intolerance syndrome that may be
difficult to distinguish from a flare of inflammatory bowel disease. Although the
exact frequency of occurrence has not been determined, it has occurred in 3% of
patients in controlled clinical trials of mesalamine or sulfasalazine. Symptoms include
cramping, acute abdominal pain and bloody diarrhea, sometimes fever, headache, and
rash. If acute intolerance syndrome is suspected, promptly discontinue treatment with
APRISO.
The symptoms you describe fit in with this. I'm not saying this is what is wrong but a possibility. Have you called your GI and reported the sudden change you have had? Have you called the after-hours number and spoken with the on-call doctor? I sounds like you need to be evaluated. Let us know.