Milk protein allergy

Has anyone had troubles with your LO having a milk protein allergy? We are thinking Lincoln has one because he has been having bloody stools. 😔 he's not fussy and he still eats and is gaining weight like a champ! So that's really great, but I'm trying really hard to cut out all dairy from my diet. Any suggestions/encouragement from people who have experienced this? Soy is ok, right?