Food allergy woes

Ever since Alana was born she's had a chronic stuffy nose, and a persistent rash that both come and go with what seems like no warning at all. At first everyone told me that newborns usually have pretty stuffy noses, and that rashes and acne are very common. So, I tried to ignore it until her nose got really bad when she was about a month old. I took her to the Pediatrician, and she said that it was just a runny nose, and to keep it clean, she was fine. So I thought, "Fine, I'll just keep an eye on it." It would come and go, and was always associated with a facial rash that would get really bad sometimes. Then I got to thinking about a little boy I used to babysit who would get horrible sinus infections and facial rashes. They eventually figured out that he was allergic to wheat. They cut the wheat out of his diet, and he was fine. So maybe she was allergic to wheat. But I thought back through the week, when she had been perfectly clear, and realized that I had wheat in my sandwich bread, so that probably wasn't it. My husband picked up McDonald's for dinner that night and Alana broke out again, and her nose was horrible. I realized that as I was getting the hang of this mommy thing I had started cooking a lot again, and we weren't eating fast food as much anymore. Also, I had tried to cut back on my guilty pleasure, peanut M&M's in hopes of losing some weight. So, I asked my sister if they cooked any of the food at McDonald in peanut oil, and apparently all of their fried food is cooked in peanut oil. For the last two weeks I have avoided peanuts like the plague and she hasn't had a runny nose or rash. Looks like I have a peanut allergy on my hands. Yeah. Hopefully I can find out for sure this week at her doctor appointment. It just makes my sad, because that means no french fries or peanut M&M's until she gets weaned for me. Oh, well, maybe I'll loose the weight faster this way. It's also really scary, because I have heard so many horror stories about peanut allergies, and how they are so deadly, the worst food allergy you could have, etc. Plus, peanuts are in so many foods secretly, I fear it's going to be worse then my coconut allergy when it comes to trial and error. I just wish I knew more about what foods contain peanuts and stuff. Does anyone have any advice for me? Are there any websites I can go to? Does anyone know what the Doctor has to do to confirm a food allergy? Above is a picture of her rash face, it's kind of hard to see because of the lighting.