Hi welcome to Health care magic forum.
Thanks for calling H.C.M.F.
From your description you had pain around the navus, and below, with foul smelling flatulance. stool pattern has changed.
The causes could be amoebiasis
, intestinal worms etc. You may need to be treated with anaerobic and anaerobic anti biotics, enzymes, and antelmenthics with the advise of a doctor for relief.
Wishing for a quick and complete relief.