Since you were in hot conditions and wearing a helmet all the time I presume you might actually have fungal infection
of the scalp
which could be caused by trichophyton, epidermophyton or microsporum which are different fungi.
The degree of tissue reaction could resemble boils and since it's itchy and been there for a while I strongly suspect i might be fungal infection. The thing is when fungus invades your scalp, shampoos like Selsun
may only heal them for a while. It would come back again and again as you discontinue the shampoo.
will see you and if he feels it's fungal infection indeed, he might put you on terbinafine
250 mg tablets once daily for 2 to 3 weeks.