My son won't eat the formula anymore. He would suck a little and then make a gagging sound. I changed the milk, the cereal, the nipple, the inserts. I DON'T KNOW WHAT IS GOING ON!!! He hasn't eaten since 2 days ago. He would eat 2 ounces and then stop. He is 7 months. It's not normal. What is going on? Anybody else with this problem? I am desperate and scared

EDIT: I apologize I left out that my baby is eating puree normally. He is NOT starving. I also hydrate him with Pedialyte popsicles as the doctor recommended. He eats cereal in a bowl with water, but not formula. I just don't know if he grew out of formula or i should change the brand. Can they grow out of it so early?