Crying over spilt milk

Today I'm pretty sure I got confirmation that Thea has a milk allergy. A friend was over and we fed all the kids mac and cheese - the organic kind, mind you, but still. Thea didn't seem too into it, choosing instead to chew on a cracker, but she took a few bites, and of course, the sauce got all over the place.
A few minutes later, I looked at her and she had bloches all over her face and a pimply rash spreading around her chin. I panicked a bit but since I had a friend here, we just waited a bit to make sure she didn't exhibit any other symptoms and within an half-hour the rash had mellowed. But I called the medical clinic and made an appointment for tomorrow.
Ever since Thea was born, I suspected milk was an issue. I'd have a big bowl of ice cream and the next day, she would be miserable. Somewhere around month two I stopped eating most large-dose milk products like drinking milk, milkshakes, ice cream, and even cheese for a while. I've relaxed a bit, but still avoid most of that stuff.
We started feeding Thea solids months ago, but it has only been recently that things have really taken off variety-wise. Since she loves to feed herself, I've been looking for things to feed her. And about a month ago, maybe a little more, she got a bad cold, then a low fever for several days, then a rash, and the trots. It cleared up for a couple days, then the river of snot reappeared. It's not like a regular cold - she is just pouring snot. And neither Liam or I got anything. And on and off, she has the runs. Also, I tried to feed her yogurt for the first time right before she got really sick the first time. And she never really liked it and if you've seen Thea eat, you know that's unusual.

So, I'm trying not to freak out too bad but wow, that's a big thing. I've been doing some reading, and often these milk allergies in infants mellow by around 2 or 3 years of age. But I've watched my sister struggle through life with a kid who has an allergy, and it's not easy. So the prospect of trying to find foods to feed this ever-hungry little thing that are milk-free, not to mention another five months of completely avoiding milk products myself is daunting.
I've got a little Charlie Brown going on right now. This has been some month.