From your symptoms, you seem to have developed amoebic colitis
post-operatively. Please get your stools examined after an overnight purge to confirm the diagnosis. Metronidazole
can cure you from this problem. Low grade fever
can be an issue of concern, particularly if it is evening fever. Such fever for prolonged period is known to occur due to tuberculosis; moreover tuberculosis of the colon
may cause the constipation
with pain in abdomen.
Monteux test might help to diagnose tuberculosis.
Please consult your surgeon or physician for the problem.
I hope this helps you.
Dr. Nishikant Shrotri