Hi, i have been getting itchy bumps in my scalp. they appear suddenly small and then grow in size getting itchy and painful, then subside on their own?

Hair dye?: You may have developed a contact allergy to hair dye (if you do dye your hair) or other hair preparations. The onset of reaction is usually from 24 to 72 hrs after exposure. Thus if you dye your hair once every month, the reaction will start in 24-72 hrs and subside a week or two after until the next contact. If you don't dye your hair, then will have to go another route.