milk protein allergy

my son is 8 and he is highly allergic to milk proteins, well i have 9 proteins to look for in the ingredients but something confusses me about "calcium carbonate" is that a milk protein? it is not on my list but you always here you get calcium through milk.

[Renee Radenberg]

Calcium carbonate is a form of calcium not a protein. Calcium is a mineral that is needed in our body for numerous processes such as building bones Milk is one of the main sources of calcium, however, you can have calcium sources that are not dairy, such as Kale, Beans, and Tofu.