Cock a doodle doo!

What happened to my good sleeper? Gannon used to sleep from 7pm to 7am without a peep. He has recently taken to getting up around 5am, turning on his light and saying he is done with his nap! We put foil on his window (we probably look like a meth house from the outside:), then cardboard, a shade, and curtains. His room is pitch black. We have experimented with his bedtime (I was told to do so slowly), which has ranged anywhere from 6:30-8:30. This morning he woke up at 3:30am! We told him he had to go back to bed or lay down with us; he laid down with us until he heard brother cry on the monitor at 5:30, at which time he said "I need milk and Cheerios". That was it, we were up. Fortunatly Beau still sleeps from 6:30pm-7:30am and takes a good two hour nap. Gannon still needs a nap mid-day so I am at my wits end trying to figure this out. I know it is a stage and I will be draggin him out of bed in a few years but I need some assistance now!