Sleeping suggestions


Okay, so I’m not complaining... more so just looking for suggestions or to see if anyone else is going through the same. My 9 week old son sleeps pretty darn well. Normally 6-8 hours the first stretch. After I put him back down when he gets up to eat, about 30 minutes later he is moving around/grunting/whining constantly. He is formula fed and on nutramigen. We went to the doctor a couple of days ago and she recommended starting a little cereal in his bottle because of his reflux. She said if it didn’t help, we could start him on medicine. It has helped so much with the spitting up already. So, why is he sleeping SO good for the first stretch, but not doing okay for the second? It’s like he’s asleep but not comfortable or something. And I do keep him propped up for 30 minutes after the middle of the night bottle... any suggestions?