Hello & welcome to HCM forum
1) You are most likely suffering from Acute Bacterial Gastroenteritis
as this condition is associated with all normal investigation (as you have).
2) As you have already undergone Appendectomy cholecystectomy
, then there is no chances of appendicitis
3) With family history of diabetes
there is high chances of mesentric ischaemia but this condition is very painful & life threatening.
4) You should also go for CT/ MRI
scan of abdomen with angiography
to rule out mesentric ischaemia.
5) Acute Bacterial Gastroenteritis is treatable and curable disease by medicine only
Get well soon
Dr. Mayank Bhargava