Reaction to pesto - what's the likeliest culprit?

[glasjam]

My 15 month old daughter has been suffering from excema since she was about 3 months old - at first just an isolated patch on her face but now the whole of her legs are dry and patchy - her trunk just had a flare up, tops of her arms. To be honest they never get really seriously weepy but she does scratch like crazy sometimes and it bleeds. Tried a few things but it seems so cyclical - sometimes it looks like it has completely cleared and then it will just emerge again.

Haven't been able to pinpoint any particular thing that sets it off - she has always eaten cheese and has had a little bit of yoghurt recently to no ill effect. She has had cow's milk once or twice and didn't react but we are keeping her off it for now.
She's never had forumula and I'm still feeding her myself.

So the other day she had pasta with M&S pesto sauce and she came up in a red rash and hives mainly over face but also on arms and legs. I left it a good few months and was around someones house the other day and they served it for lunch - I took a risk and the same thing happened. It happened almost instantly and she was most put out when I took it off her!

So the obvious one is pine nuts isn't it? I have eaten snickers bars occasionally when breast feeding and have had cashew nut butter - perhaps this has also gone through the breast milk? Or could it be pecorino cheese?

I myself have a wierd and inconsistent reaction to cheese - usually plain old cheddar. Sometimes just opening a packet can cause my face to flush noticably (my other half always asks if I've had any cheese recently). So I am wondering whether I have a mild cheese allergy - or possibly annatto? It just doesn't happen EVERY time.
And I LOVE cheese!

Any thoughts especially guidance on how I should proceed with regards to nuts in general - completely steer clear myself whilst breastfeeding? Keep her away from nuts till she's 3? Have her tested?

Any help will be gratefully received.

Bruffin that's interesting - how old was he when he was allergy tested? What happened when he came into contact with nuts then - was it a rash and/or swelling? Has the testing shown that he has grown out of peanuts? Just trying to get my head round all of this so it is great that people are coming back to me with their own experiences - finding it really useful!

Ds's allergies didn't really start until he was nearly 5, although we suspected seseme before that.
He had a weekend where on the Friday he had a cake covered in seseme seeds and threw up, then on the sunday he had a pecan pie and his face swelled up, he couldn't stop sneezing, mouth filled with copious amounts of saliva and he ended being sick again.

Had a bit of a struggle with a gp about getting testing, so he wasn't tested until he was nearly 6. In between he could no longer eat things like chocolate spread or peanut butter which he had eaten before. RAST test showed allergies to all the treenuts he was tested for, seseme and mild allergy to peanuts.
He has come out in hives two or three times, although we never found out what the cause was. Although not tested I am sure he is allergic to sunflower seeds and poppy seeds.

Had him retested at 12 and RAST test showed still allergic to tree nuts except cashew, seseme,hayfever and cats, but not his guinea pig, thank goodness. He does also have a problem with chronic sinusitis which caused by some sort of allergy.

He has tried a little bit of peanut butter since and he had no reaction at all.

pine nuts imo is the likeliest.