As per your complaints it seems Acute Gut Infection/Acute Gastroenteritis
Red flag signs in AGE are
3.Decrease urine output
4.High grade fever
The cause of stomache in you child might be Colicky or Acute Abdomen
.As per symptoms
you have described you should consult with your pediatrician
Some basic investigations like complete blood picture,serum electrolytes, renal function
tests and USG abdomen should be performed.
Wishing good health for your child.