hello there, i think you should go to a pediatrician to get your son evaluated for high eosinophil counts. usually this is seen with parasitic infestations and some blood or immune system disorders. your son will require certain investigations like peripheral smear comment specially for microfilaria, and any atypical cells. stool routine and microscopy should be done for ova and cyst. may be he will need some other blood investigations for for immunoglobulin estimation specially for IgE. this swelling that is present may be a swollen gland (lymph node or some kind of granuloma (a king of inflammation). generally this occurs after any infection in the draining area of the gland or some other blood or immunological problems. you may get the diagnosis by either a fine needle aspiration cytology or a biopsy if needed. blood investigations mentioned above may also give a diagnosis. so please consult your pediatrician and get him investigated accordingly. thank you amit