Thank you for your query.
These are symptoms of malaise
.He might be starting to show symptoms of an oncoming viral infection.
Give him some rest and keep him on fluids.
If he has nausea
and deepening yellowish urine he might have have jaundice
Keep a close watch on the child and consult your doctor if he falls sick.
If you have any further queries you are free to consult me.
Hope this answers your query.
Wishing your child a speedy recovery.
Have a nice day.