3 month old STILL spitting up!!!?

My son has been spitting up after and between feeding since he was born. His pediatrician switched his formula to Enfamil A.R. He seemed to spit up less once I started the A.R. But now it seems he is starting to spit up ALOT more than usual. He eats 6oz with rice or oatmeal every feeding. I burp him at 3oz and when he is finished. Sometimes it looks like his mouth is a faucet. And it is chunky. What else can I try?