Hi It looks like you have an excessive secretion of oil or sebum over the scalp.  In this condition the oil glands associated with the hair glands get infected and cause folliculitis. This is what the pus and pain is due to. recurring infections lead to hair loss. Stop oiling your scalp and try to exercise and eat a healthy diet. This reduces over all sebum secretion. Use a shampoo for oily scalp containing selenium sulfide and or ketoconazole. If there is no improvement do visit a dermatologist so they can start you on oral medicines