Dairy Allergy

HELP. My baby is 11 weeks old and over the last few days has had extremely watery diarrhea and only pooping about 1-2 times a day. It seems that every time she is trying to pass gas or poop she gets extremely fussy and starts crying/screaming until I feed her. I haven’t noticed any blood or mucous in her diarrhea but she has been spitting up like crazy and is so restless.

How did you know your baby had a dairy allergy? I feel so bad for my girl 😭 she has all the signs of a dairy allergy but it seems to have come on so randomly.