Hi nearly, sounds as though you have had a frightening experience, I don't blame you for being in shock!
In our case, ds had a skin reaction to raw egg white at about 3 months old when I accidentally got some on him while I was baking. We had him skin prick tested privately (we were told that there would be a long wait for NHS testing as he was not allergic to milk) and found that he is also allergic to cashew nuts. Egg and nuts/peanuts (which are actually a legume rather than a nut) have similar proteins, which is why children are often - but by no means always - allergic to both.
The eight most common allergenic foods are egg, milk, peanuts, tree nuts, fish, shellfish (although I think these two are most often adult-onset allergies), soya and sesame. There are others that are becoming more common, such as celery and mustard. All of these have to be listed by law on the ingredient panels of pre-packaged food. If you have already started weaning your DS, he may have already eaten some of these and be fine with them. If there are foods on the list that he has not already eaten, I would personally wait for your appointment and testing before introducing them.
Your choice, but if you choose to introduce them before seeing a specialist, bear in mind that an allergic reaction does not necessarily happen on the first exposure. DS has now had all the foods on the list apart from shellfish, and I introduced them all by rubbing a tiny bit on his cheek first, then his lip, then his tongue, all at intervals of at least ten minutes. This was in spite of having clear RAST and skin prick tests - I err on the side of being overcautious!
I didn't think that my consumption of egg was affecting DS through my breastmilk, but he did have a couple of small patches of eczema that have disappeared since I cut it out of my diet, so who knows? I have to say that I did start to manage the eczema better once I knew about his allergies, so the jury's out on that one. I worry more about him inadvertantly coming into physical contact with them if I eat them, so I do not eat egg or nuts at all. In fact we are an egg and nut free house at the moment while I try to get my head around the whole thing!
The good news is that egg is one of the allergies most often outgrown, so there is every chance that it will not be lifelong for your DS. They test for both raw and baked egg, as the protein changes with cooking, so it may be that your DS might start to tolerate hard-baked egg, ie cake, before raw if he starts to outgrow.
It does get easier. DS turned one yesterday and I managed to put on an allergen-free spread for the family with a really lovely chocolate cake (I'm going to start a thread and post the recipe it was so nice!) These boards have been invaluable for me - there are many lovely ladies here who are much further down the road than we are and who have loads of really useful advice and knowledge that they are more than happy to share.
Good luck, and keep posting!