Can a toddler develop an allergy to milk?

My 21 month old has been throwing up lately, and it seems to be every time she drinks milk. She's been drinking milk for 8 months with no problems at all, but now she's vomiting alot. (No fever or other negative symptoms) Some suggested that it may be a lactose intolerance, but after researching that, it seems that the result would be diarrhea, not vomit. Others suggested an allergy to milk, but can a child suddenly become allergic to something that she's previously had no problems with? We're going to the doctor on Monday to be sure, but I'm, trying to ease my mind now! In the meantime, she's drinking Silk soymilk with no problems. Thanks in advance:)

I am a father of 3 and all 3 have had problems with milk they had the same issue of vomiting after drinking milk. Our Dr said it was lactose intolerance. A few other sugestions you could try milk with a lower milk fat such as 1% or skilm that has helped with one of mine then there is a product called Lactaid you can buy it at the grocery store that is basicly milk with no lactose. That worked with the other 2. Hope this helps

Yes they do. I am 40 + and can't do milk. Every person reacts differently. No matter what you read about. All milk isn't made the same. It's a strong possibility that something in that milk could be the cause.

You may have just answered your own question since she doesn't have the problem with the soy milk. A person can develope an allergy to something anytime not just the first contact.