My ds is allergic to dairy and eggs, and then found to be allergic to peanuts (haven't dared to try hummous however much I would love to). Can you call the allergy clinic and tell them his reaction (i.e. possible anaphalactic) and get them to bring forward the appointment. Knowledge is power and all that!
I had the same experience with my son (17 mths), very red face and swollen hands where the houmous had been in contact. He's now been diagnosed with dairy, egg, nut and sesame allergies. I don't know how old your son is but I would say don't give any nuts at all until he's been tested. The advice is not to introduce nuts to any child with allergies until they're about 3 (that's what the hospital told us anyway).
My son doesn't react to any other legumes luckily. The main thing to look out for is cross contamination. I do gamble a bit with the 'may contain' label on some foods, sesame is on a lot (probably shouldn't I know). The only problems we've had so far has been with bagels from the bakery in supermarkets and also some Italian breadsticks so we now avoid these.
My son's reaction has been worse every time but I think we've only had 3 exposures (2 due to contamination rather than sesame being in the ingredients). We've been told that kids have to reach a minimum weight before you can use an epi-pen and our son is too young/small for one at the moment.
Look out for sesame seeds and flour in other products like the Kellogs "straws". They have sesame flour in, so do some breads and other biscuity things. They will say there is sesame in but it is worth checking. My daughter had half a Kellogs straw and her whole face swelled up.
BUMP! My DS (3) has just had a bad reaction to houmous, throat swelled up and got hives around his mouth... Waiting for hospital ap. which seems to be taking forever! Does anyone know what else he should be avoiding?
Sorry to hear about your DS. My DD 4yo had the same reaction to Houmos - only tasted a very small amount and ended up in A&E. RAST tests showed high allergy to sesame seeds and chick peas and mixed nuts (she has never had nuts). She was given epipens due to high result. She also has severe eczema, and allergies to grass pollen, dogs and cats amongst other things ((big sigh))
She then went on to have a full anaphylictic (sp?) shock to some soup which contained lentils (this was about 6 months later). Allergy clinic didn't do any further tests, just said it was the lentils as they are legumes like chick peas and peanuts. It was scary though and was very glad we had our epipen which worked really quickly.
I know everyone is not the same, but I just thought I would share. I wish I had known about the lentils before I gave her the soup - I checked for all her allergens and thought it was safe :-(