Hello! I have been through your question. Related your concern I think you should exclude the most probably an infection disease called borreliosis (lyme disease) caused by a spirochete (Borrelia burgdorferi). Most people get Lyme from the bite of the ticks, and it is most common in children, older adults because they have higher exposure to ticks.You should know that approximately days to weeks later, the infection causes in the skin around the bite develops an expanding ring of unraised redness that is often associated with flu-like symptoms. What I suggest for this situation is doing as soon as possible a physical examination by an Infectious diseases specialist, full blood count, serology for borreliosis and take the prompt, adequate treatment . I hope my answer help you. I wish your son a quick recover .