If you have pustules, on scalp
it could be bacterial infection and treatment differs.
Did the doctor confirm ,that it's male pattern baldness
, if not, then Tinea
infection can also lead to patchy baldness with itching for which the treatment is different. Are you on any other medication and do you have any other illness, needs to be assessed.consult a dermatologist
for full clinical evaluation and treatment.
hope this helped you , Take care