Starting on Saturday my son woke up early in the morning screaming and crying. Complaining that his right knee hurt and that he couldn't move it. Since then at some points he can stand on it but its always with a limp and other times with INactivity it would get to where he couldn't walk again. On day two a rash started that covered most of his body. It is now almost gone after being treated with benadryl and hydrocortisone cream. He has a constant low grade fever and very swollen lymphnodes in his neck and under his arms, worse on the right side. Although with plenty of rest his knee seems to slowly be getting better he still has swollen lymphnodes and a fever that won't go away. If it helps any he was sick about a week and a half before with a stomach bug/sore throat, and even though that is all gone he got sick a few days ago but just the once. Does anyone have any clue as to what may be going on with my son?