Hi welcome to Health care magic forum.
Thanks for sending question to H.C.M.F.
Your 4 year son had stomach pain 9 days ago. About 6 days ago he had fever, for 3 days, and had pain abdomen loss of appetite, and nose bleed.
All these symptoms appears to be directing towards the same disease, enteric fever
with upper respiratory symptoms as well. Nose bleed may be due to upper respiratory symptoms.
I advise you to consult a pediatrician
for diagnosis and treatment. You may have to undergo a series of tests for confirmation. Don't worry he will be fine soon.