you are having lump behind your ear and itchy scalp
Hope you are not having a discharging ear then it could be because of seborrhic dermatitis
on scalp and that lump is an enlarged swollen lymph node.
You should meet a dermatologist
You can start with medicated anti Dandruff
shampoo twice a week. Do dry your hairs before combing or covering them with cloth or cap.
Most importantly should not scrap your scalp otherwise it may start bleeding.
If you have excessive itching you can take antihistaminic tablets .
get well soon.