Allergic to eggs, xopenex or oil?

My twin boys have had about 3 bouts with respitiroy wheezing/coughing due to virus's. My 5year old has "asthma" symptoms when he gets a bad cold. My boys all use xopenex and have for each wheezing/coughing episode. The last (about 3 weeks ago) coughing episode I started my younger twin on xopenex 1x during  day and his daycare provider said  that his face got a little red after they gave it to him, but that he was fine. The past week he has been a little under the weather with the usual virus stuff..running nose ect.
This morning we had french toast (hes had plenty of stuff with eggs in it, ie muffins ect, but never straight eggs) and apples for breakfast..afterward I noticed he was wheezing so I gave him a treatment. Then his face arms and torso get splotchy red and white raised bumps. The bumps were really bad around his neck and arm creases. We got really freaked out so we took him into the hospital. On the way he puked all his breakfast up, but wasn't wheezing by the time we got there. At the hospital they hooked him up to monitors, gave him a dose of steriods and benadril. They also took blood. The Dr said everything looked ok other than the tests showed he did have a virus. All is well now, he just looks a little pale...
Sorry for the long story...I just wanted to know could he possibly be allergic to the xopenex even know we've used it before, or could he be allergic to eggs since the french toast was dipped in egg before I fried it. The only other thing that was diffrent that morning was I cooked the french toast in expreller pressed safflower oil. The Dr said that it could have been the virus...not sure??