Hello and welcome to healthcaremagic
I have gone through your query and I have understood it.
I would keep a possibility of seborrheic
dermatitis with secondary bacterial infection.
I would suggest you an antiseptic shampoo or scalp wash e.g cetrimide 5% solution for scalp wash daily. Cetrimide is antiseptic as well as antiseborrheic and would thus remove adherent crusts and scales
If I was the treating doctor I would have suggested an oral antibiotic for a week.
My choice of oral antibiotic would have been either:
Amoxycillin 500mg in combination with
clavulanic acid 125 mg, thrice daily for a week
OR
Ceplhalexin 500 mg thrice daily for a week
OR
Cefadroxil 500 mg twice daily for a week.
An OTC topical antibacterial e.g 2%
Mupirocin twice daily can be applied over the boil.
An OTC pain killer e.g Ibuprofen 400mg (bruffen tablets) twice or thrice daily, would provide symptomatic relief from pain and swelling.
I hope this answers your query.
Regards