My 4 yr. old son took a dose of Zithromax yesterday evening, he then took a nap when he woke up he complained that he could not walk because his legs hurt. This morning he would not try to walk he was standing with my help on his tippy toes and crying from pain. I took him to the Dr. And the dr. Said it is probably a virus and gave him a steroid shot and sent us home. I am still concerned because he is still complaining with pain although it does not seem to be as bad.