Thanks Sonoran Silkies. In answer, I think (without digging out his records) that his weight started in the high sixties, then dropped steadily until now it's 30. Last visit was 57%, I believe. And that was prior to starting to crawl.
Spitting up? No, he almost never does this.
We have a white noise machine going in his room all the time and I'm about to set up one of those lights that puts the constellation on the ceiling and rotates it. I'm hoping that it mesmerizes him a little bit.
We start our bedtime routine at 7:00 or 7:30, and it's usually no problem for him to sleep (very broken up) until 7:30 in the morning or later. The past two mornings it was much later. So when he's not even willing to give me that late wake-up, after terrorizing me all night, I get VERY frustrated and weepy.