M.C.
M.,
You may need to move away from the soy and milk based formulas. They are definitely an issue for kids with allergies. There are choices that are not soy or milk. The doctor should be able to provide you with other options to fulfill the nutritional needs. As far as the testing goes, you may want to ask the doctor to do skin testing instead of blood testing.
I am a person who as a child was allergic to soy and milk products and had the same reaction. There are definitely other things on the market. Wish I knew what they are. Sorry, but good luck.