Thanks for query,
You observe for following,
1,does he having some temperature.?some time due to low fever child do not like to take and asks for water,
2,See the colour of urine,weather is it yellow,in inf. hepatitis
there is loss of appetite and nausea
3,some time a child has warm infestation causing loss of appetite and stomach upset
Consult your doctor and discuss all these and find out the cause.
ok and bye.