I htink it has a lot to do with developmental milestones. Erin was my worst by far - first it was cause she couldn't sit up, and then when she mastered that she was grizzly cause she couldn't move, then once she started crawling it eased off a bit. It wasn't too bad just before she started walking, cause she was already shuffling upright on her knees, so walking was just a progression of that.

I hope it is because he either wants to get moving or his teeth come through.