who needs sleep?

for the past 6 mos or so, val has been waking between 3 & 4 in the morning & never going back to sleep. & skipping naps, despite being so exhausted he can barely make it through lunch. he begs to go to bed at night, but it takes him a minimum of an hour ot fall asleep any given night. the poor baby is getting maybe 7-8 hours of sleep in any given 24 hour period.
he's never been a "good" sleeper. he's always been up & down several times throughout the night, although he rarely needs us to go check on him beyond an occasional (speedy & quiet) diaper change. he doesn't cry or complain, just chats quietly to himself for hours at a stretch.
we have tried EVERYTHING imaginable to help him sleep. moving bedtimes, changing nap, eliminating nap, extending nap, waking earlier/later, changing snacks, changing dinner times. we have a steady, calm, bedtime routine every night involving a warm bath & a story. (works like a charm with the other 2.) we've conferred with other parents, the grandparents, the nurses at our doctor's office & nothing has helped or altered things in any way.
at first, i was willing to roll with it, since not all kids are good sleepers & with 3 such little kids in the house it's not like we get much sleep to start with. it's starting to effect his personality though, as well as his ability to focus. he's struggling in speech, he's whiney & unhappy & i know it's bc the poor guy is just exhausted all of the time. i know how awful i feel with consecutive days of no sleep, & i hate that my 2 year old has seemingly unexplained insomnia. we have an appointment with his pedi tomorrow morning. (the nurses we've been talking to at the doc's office finally agreed it was not normal toddler-sleep-issues & i am at my wit's end. i hate to seem him miserable when he's usually such a happy kid.)
there's not much point to this post, beyond the fact that we're all really tired & i'm worried about val. happy sunday kids!