He usually does this after eating. It has always confused me and I couldn't find anything online. The other birds have never done this, only him. I have never seen another bird do this (and I have seen a LOT of birds). I hope someone has an answer, he doesn't seem to be in pain but it seems involuntary which concerns me somewhat. He has also had times where he was doing in and looked like he wanted to stop but couldn't. Any insight would be greatly appreciated.