It seems like you are having Seborrheic Dermatitis,which is an inflammatory condition of the scalp and skin and the skin becomes more sensitive to the yeast called Malassezia
is an uninflamed form of seborrhoeic dermatitis
Following is the treatment of the SD.
1: Nizoral AD shampoo,three times a week for 4 weeks initially and then whenever required.
2:Betonil lotion,should be applied and massage through hair every night for 10 days,every other night for 10 days, and then whenever needed.
3:Tablet Zyrtec 10mg,once a day for 10-14 days,its an anti allergic and should help in irritation and itch.
Regarding the bump behind the ear,there are two possibilities,one: it could be a Ptyrosporum folliculitis
due to SD or it can be an enlarged lymph node
due to the inflammation going on in the scalp.Both of them will relieve after treatment.
thanks very much and all the best.