Welcome to health care magic.
From our description, the rash behind your ears could have been seborrhoeic dermatitis
. It could have got infected because of constant handling or scratching. This would probably be the cause of the abscess
or boil which you are now feeling as a painful lump. You need a course of antibiotics which will heal the boil. For the rash, please consult your doctor to confirm the diagnosis. Topical steroid
creams will help to clear the rash.
Hope this helped you.