E.G.
It sounds like your son may be addicted to rice cereal. I suggest weening him from it. He's not satisfied with more nutrional foods because his body craves refined carbohydrate(rice cereal). There's a school of thought that babies should never have rice cereal. It's void of nutrition and creates a high glycemic reaction. In other words, the more you give him the more he wants. He won't be satisfied until he's uncomfortable. It's also why he needs it to fall asleep. Are you aware of the type II(adult onset) diabetes epidemic in children. I reccomend doing some hard research on nutrition as I am not an expert. Frankly, a doctor who reccomends giving an infant rice cereal at bedtime is no authority either!
I wish you and and your family the highest and best!