I have a pink scaly patch on my scalp for a long time which has gotten bigger and will not go away what could it be?

Patch : Scaly patches on the skin could be many different entities but on the scalp likely seborrhea or psoriasis or possibly fungal skin infection. I would see your doctor to fully evaluate.

Lots of things: but psoriasis is my first thought. Your MD can look at it and tell. If it isn't obvious they can take a sample of the tissue (a biopsy) and tell that way. Very rarely, skin cancer presents this way , too, so see your doctor. It isn't an emergency, but it is important.