Welcome to HCM,
As all reports are normal but long h/o abdominal pain
and now diarrhea
suggests that you might have chronic gastro-intestinal infection, either bacterial or amoebic.
Go for stool test
to find out nature of infection and afterwards go for specific treatment accordingly.
take light diet like buttermilk, curd, rice.
Avoid fried and junk food.
Ok and bye.