4 week old ALLERGIC to dairy/milk!

I took my daughter to the emergency room tonight at a children's hospital because of blood in her stool like 2-3 times a day for about a week or two, and come to find out that my baby is allergic to the protein in milk. I was using my breast milk and I was also using formula. And I love milk myself so now they gave me a different type of formula: Similac Alimentum and this is for babies who are food allergic. And if I still want to breastfeed I have to stop eating dairy too. I do plan to breastfeed still because I don't want my milk going to waste whenever I pump. So I'm cutting out the dairy for my baby girl. It's just so sad knowing that she's allergic to milk, I hope it's just a temporary thing, and not a lifetime thing, I think it would be hard to raise a lactose child, I would have to watch everything she eats, but I know God is a healer.