my son is 2/12 years old and he has had 6 ear infections so the docter put tubes in his ears then he had four more ear infections most of them were middle ear infections they took blood cause i demanded it and it showed that he did have an infection so they put him on a antibiotic and then i noticed a tender lump behind both ears and a hard lump above both ears and he tells me that it hurts a little and they have been there for more then 3 weeks and they have not changed what could this be please help.