T.H.
Is he on formula? If so, try the formula designed for spitting babies...I think Enfamil makes the brand name but Target does a generic. I think it just has rice cereal in it to make it thicker but it's ground up so fine that you don't notice. I don't know if I'd recommend that you put cereal in the bottle though. At four months, he could start on rice cereal by spoon. We started my son that early b/c he was on soy formula and was just never full, so it might help, it gives them more substance in their bellies. If you're breast feeding then I would cut out all dairy products and see how that goes. A warning though that lactose can stay in your system for many weeks, so you may not notice a huge difference right away but give it time.