Help with heat rash problem?

i have had heat rash since 3 almost 4 days ago..it goes in the evening and morning...and in between it is blotchie...its not prickly heat..i put calimine lotion on..aleovera straight from the plant and it has seemed to have gone down more than any of the days,im going away tomorrow to a party and i'm wearing a boob tube dress,if i wear p20 on my chest (where the rash is)..would it be okay?..