Could this be a peanut allergy?

DD has had a rash on her labia & buttocks coming & going since September.  I've taken her repeatedly to the dr.  They keep telling me contact dermititis.  Asked me about detergent, soaps, whether she's wiping well, all kinds of things.  We spent a month not letting her wipe herself, we stopped using Cottonelle wipes in case she was reacting to the fragrance, we tried cortisone cream, we tried nystatin cream.  None of it helps.  Then, suddenly it will disappear, only to reappear a few days later.

At first I thought she was having an allergy to milk, since she had a milk protein intolerance until she was 3.  But we cut out milk products again & she kept getting the rash, and reintroduced & the rash didn't get any worse.  Then it started popping up on her cheeks next to her mouth.

It's been getting worse & worse on her face.  Now her entire mouth, lips, chin & cheeks next to her mouth are covered with what looks like eczema (bright red, rashy looking, then the next day it gets dry & scaly & starts to peel).  I am now thinking it might be a peanut allergy, because yesterday for the 3rd or 4th time I noticed she was fine all day, had PB&J for lunch (which she does every day, since she couldn't have milk & I needed to give her protein), and within 2-3 hours she had the rash all over her face.  And I'm thinking the coming & going of the rash may have something to do with us having her on Claritin for her seasonal allergies every day, and come the fall, we gave it to her but not every day, depending on how high the pollen was.  A few weeks ago, we stopped giving it to her altogether, and that's about when the rash on her face started.

I'm keeping her away from all nuts for the next few days to see what happens, but I'm thinking it's time to ask the pedi to send us to an allergist.  Any experience with this?