What Causes Redness And Itching On The Face?

I took whitening facial yesterday afternoon then went out for shopping. In evening there rtwo red spots below my right cheek and gradually my both cheeks, forehead and sides of neck become red. I took one Avil 30 table today morning. redness is less, little bit itching is still there and also there is little burniing feeling. tell me wht happento my face? is it cosmetic allergyor something else?
tellme wht dose of avil 50 shud i take in a day?

Thanks