Hello,
It can be a pilar cyst, dermoid cyst or some benign growth of the scalp. Pilar cyst is a benign cyst on the head and neck which is mostly painless but can become painful when infected. Since it has been present for 5 years, it would be better to get it examined from a dermatologist and get a biopsy done to confirm the diagnosis.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
The skin gets thick and very dry (like crusts) at this particular location...