your son might be developing viral myalgia
. it begins with all these symptoms & most often associated with fever. if he has no other symptoms other than lethargy
, he can be observed at home. he needs to take adequate rest & plenty of water. he needs to eat as much as he can & what ever he can so that he feels much bettter. if any symptoms like fever, jaundice
etc develops, he needs to see doctor immediately. abdominal pain
can be just because of not eating adequately, if he feels better after eating then should be okay else will need to see doctor if it worsens.