Hmm, normally frequent wakings at that time of morning indicate some type of discomfort or hunger. If you don't think his tummy is hurting from the solids, could he in fact be hungry? Lots of LOs have a growth spurt raround 6mo. I can't remember if he has a DF or not? Have you tried feeding in the early morning to see if it helps?
The other reason for wakes like that is UT, but his routine doesn't suggest that, which is why I'd think hunger or discomfort. What about something environmental, like temperature? Could he be getting cold at that point in the morning?