He has a multitude of allergic symptoms over the years but we don't know what is causing it. My guess is we have several things going on and since some of the symptoms seem to be worse lately I really want to check it out since we do have family histories of allergies (environmental and food) in our family.
To start out with from the beginning DS could not tolerate regular formula and because of a family history with soy he had to be put on the hypoallergenic formala Alimentum ($$$$ - thank goodness we are done with it). Over the years we noticed that he vomited whenever he ate eggs (not baked in stuff but things like scrambled eggs and/or items with lots of egg content like french toast) so we just had him avoid all eggs and items with lots of eggs. He also has had big dark circles under his eyes for a long time that the doctor says are indicative of allergies. We put him on Zyrtec for a while but it didn't seem to help with the circles so we wonder if Zyrtec is not working on the particular allergies he might have. In addition he has broken out in rashes on and off for years that we have never been able to pinpoint the cause. The rashes seem to have gotten worse lately and appear to be bothering him more since we notice a lot of scratch marks on his torso.
My biggest concern is that he has a milk/dairy allergy and I really would like to get some confirmation if that is the case.

My DS was never a big milk drinker until he discovered chocolate milk a few months ago and I am thinking the increased rashes may be related. His behavior the last few months has also been off and while it could just be a phase or bad parenting my understanding is that allergies can have an impact on behavior so we are curious about this as well.
I hate to put him through the testing but it is at a point where I really feel like we need to identify any possible allergies so we can make some changes to see if it helps things. Thankfully he is a real trooper when it comes to doctors and shots so I hope it won't be too bad. The office told us to bring a DVD so he can watch a movie while all of this is going on.
I appreciate all your info! I like to be at least a little prepared because I know he will have lots of questions for me.