Rash on chest and neck on 7 month old

[bigchangesabound]

I have been weaning my 7 month for a couple of weeks now and it has mainly been going well. However there have been a number of occasions, after giving her certain foods, where she has flared up in a hot, red, itchy rash on her neck and chest. She scratches it like mad and is in obvious pain/discomfort from it- screaming and crying. The foods she has reacted with have been dairy, egg, strawberry, peanut butter. However she has since had more dairy and strawberry foods and has not had this reaction.
The 'flare up' as I would call it only lasts 20-30 minutes and then she is perfectly fine and happy. Although was a bit longer and more severe with the peanut butter.
I have been to the doctor but they have been next to useless, blaming it on her excessive dribbling as she is teething (her dribble is not that bad) and eczema. I have been prescribed a number of eczema creams.
Once the flare up dies down, the skin is very dry and eczema like and I do apply the creams then.
Was just wondering if anyone has any advice/experiences of this?