Milk protein allergy?

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Anyone else's little have a milk protein allergy? I would like to compare symptoms with you. I'm feeling a bit unsure about the diagnosis at this point. 
I breastfeed so I have to cut dairy out of my diet if I want to continue to breastfeed. I have done so, but it is really tough. We didn't even discuss what other options would be... I'm guessing switch to formula? I really don't want to do that. 
My issue is, I was already doing a fairly low dairy diet when the symptom of blood in stool appeared. The day before and up until that I really had hardly consumed much dairy at all. At Drs office her stool was negative for blood. Additionally at first, I was consuming much more dairy yet symptoms of an allergy didn't show up until 3.5weeks old, does that seem odd? Wouldn't they have shown up sooner when my dairy consumption was higher? 
Overall I will do what's best for my little one and obviously cut dairy at this point because that's what they suspect to be the allergen, but I'm still left wondering if she's actually allergic to something else.