Allergy to...something

Oliver (almost 18 months) developed a little rash on his knees about 6 weeks ago which i thought was excsma and last week when at doctor for a cough (actually bronchitis..oops) doc said yes excma.   however, a week later it is all over him and she says now is an allergy, to...something. thankfully its not bothering him at all but wondered if anyone had had anythign similar and figured out the allergy. it is like lots of little goosepimples and has gone, legs, arms and now his back seems to be breaking out. nothign i can think of in washing powder etc - but if it was a reaction to something which touched woudl it only affect the area it touched? food wise i thought eggs but again i dont' know if it shoudl get better once the food has been stopped or if it will not get better for 3-4 weeks - doc no help on that one. other obvious is milk but seems like a big thing to switch to non dairy.    as i said its totally in offensive to him. he also has a wheeze which i thoguht was just 'baby ongoing cold' but am wondering now if a food thing. any suggestions much appreciated. thanks,

I have had a lot of experience with allergies, myself, my children and my own siblings. The best thing to do to elliminate food allergies is to stop giving it to him for 3 days then try him on it again and see if he reacts.
Or even stop for a week if you can and see if his excema clears up. It is hard not to eat dairy or gluten for a week when you are used to having it as part of your every day diet but it is a good way of telling if there are food allergies there.
My brother and sister used to get coughs, wheezy and excema from dairy products, and as my doctor put it 'cows milk is made for baby calves, not humans' lol
Good luck!