S.R.
Is he spitting up or throwing up/vomiting? Based on my own experience with my first son, I'd look into food allergies if he is throwing up/vomiting. New foods should be introduced one at a time and you should give each new food for at least a few days before trying something new. The majority of food allergies fall in the following groups (however it is possible to be allergic to any food): dairy, egg, fish, shellfish, tree nut, peanut, soy, and wheat.