Suggest Treatment For Increasing Dark Patches In Underarms

1)my age is 21 , height 175cm , weight 80
2)medical history of skin disease ::some hard rashes at underarm due to heat in body(said by dr),small usual pimples on face

problem:
from past few years i am having small dark coloured patches in my both underarm,initially they were small bt they r increasing gradually , it do not hurt rather it feels soft on those patches.Also i have big pimple in underarm and it hurts.