Once I Used A Face Pack And My Skin Got

once i used a face pack and my skin got some infection, after that i have steamed my face to remove chemicals. it became more worse, afterwards my face skin got darker. if i use any soaps or any thing in my face, it becomes darker. i am using only green gram powder for my face. i had a kind of psoriasis and now its cured 70%. By this time to get my face color back what i have to do.