What the.......?

Ok. Per doctor's orders we have completed the 1 full month of no dairy for Madison. Our instructions were then to slowly reintroduce dairy and see what happens. So May 1 we did. She had a piece of cheese. Day 2 she had 1/2 of a yogurt. Day 3 she had a glass of milk. So far, she hasn't had any adverse reactions at all - no vomiting! I should be celebrating, I know. Yay, no milk allergy, right? But if it wasn't that then 1) what WAS it? and 2) why did it go away when we took dairy away? OR could it still be milk allergy......is there such thing as an allergy that builds up? Could she be allergic but only have a reaction if she has more than a certain amount,, or if she has dairy products every day for a certain amount of time? I'm so confused. If she isn't reacting to dairy anymore, then the doctor most likely won't order the blood tests. She'll say "well, she's ok now, no need for testing". That means we won't know for sure. We will just wait until it all happens again and start over again???? Aaaargh sometimes doctors frustrate the heck out of me. I want to know WHY she was throwing up almost every night for a month.