2 1/2 year old with major sleep problems

I know it is common for toddlers to not want to go to sleep, but my toddler seems to be on the extreme end of the spectrum with this and I don't know what to do anymore. He has never been a good sleeper, but in the last 3 months it has become a real concern. He won't cry, but will sit in his bed staring at the wall for up to four hours before falling asleep. The other night, he crashed at 6 pm because he had not slept much the days before and then woke at 2:40 am and never returned to sleep. I got him out of his bed at 7 am.

His diet is healthful, we do not watch tv in our house with him, we have always had a relaxing bedtime routine, and the list goes on....but still this child won't sleep. His pediatrician said he did not see markers for autism. He noticed my son was a little wild, but I can honestly say that when he is tired, he gets increasingly wild. The days he actually gets somewhat normal sleep (which are few and far between), he is a calm and articulate child. The days he doesn't, he seems totally scatter brained.

He mentioned melatonin and I gave him .125 mg tonight so we will see, but I am worried about giving him a hormone. What else can I do? I am desparate to help him.

Holly