Hi,
I am a Muslim, and i believe it is completely ok, as you said your son was crying. but all you need to do is to take your son at some corner or some kind of hidden place, let him eat and then do your shopping.

ofcourse food in the hand of your son while you walk all over the places is not ok. there is no legal issue in this but it is just not ok with this culture.

have fun

byeeeee