Welcome to HCM,
The child suffered chicken pox
which is a viral infection but,he is lethargic and not taking food, and having cough
It would be advisable to see a Pediatrician
and take his/her advise as he is only 2 years.
Please do not ignore it and see doctor as soon as possible so his actual condition is assesed and proper therapy may be given, if there is any jaubdice or some thing.
It is also for your information that a Vaccine
for chicken Pox is available, although it is not for this child but otheres who have not suffered can be benefited by this information.