Welcome to the board of Health Care Magic,
Probably your child suffered with some viral fever
Leg pains could be because of some after effects of fever and also some electrolyte loss due to the fever. I ill assure you that these all symptoms will recover in day or two, You encourage the child to take lot of liquids and electrolyte solution. Probably some antipyretic
syp) is also required for one or two days.
Hope your query is answered