Food Allergies Treatment

My 2 year old son is often constipated. We tried laxatives and several juices. but until now he remained that way. I heard that some children have allergy on cow’s milk, so i want to introduce soy milk to my son. Would you please tell me, the available brand suitable for young children. Thanks in advance for your info & advice. God bless.

Hi !¸
My daughter is almost 5 months and showing definate interest in eating. She has severe cows milk protein allergy ( throws up every time I drink milk or milk products– I’m breastfeeding– then has explosive diarrhea) and wasn’t gaining weight until we figured it out and I eliminated dairy from my diet.
My question is this; the nurse at my doc’s said to be watchful of baby cereal, most contain milk proteins. If it says can be diluted with water, then it probably has milk powder inside. Do you know a brand of rice cereal (the one recommended for starting) that contains none? Also soy is not an option, because of the milk allergy, I have to wait until she is at least 9 months because of greater risk of allergy. And what should I dilute it with ? Water ?