I have a rash on my face..of all places!?

I have a rash on my face, I have already been to a dermatologist and at first she was sure that it was a std but I was tested for everything under the sun and I have tested negative. No surprise there. But the rash even has perplexed the rash is symmetrical along the sides of my mouth it reaches from one end of my smile lines to the other side. Its flat and it was peeling for a minute, itchy at times, and red at times. right now it really stands out because by me having darker skin its light and discolored so it really stand out. We are considering allergic reactions and cant think of anything new Im eating/doing the only thing is I have started eating cereal(raisin bran), and Im slightly lactose intolerant but I am able to drink a little milk with no problem, I haven't changed laundry detergent i use tide(im allergic to downy). What could it be it has really effected me I feel so ashamed, I feel compelled to tell people who ask that I don't have a disease. Please any suggestions will help. BTW the doc took a sample from a rash under my arm(which I say has nothing to with the one on my face its an old allergy to a deodorant I used)so the results from that I am waiting on. Will this ever go away its been at least a month now.