R.S.
As my son got a little older (past 6 months or so) he needed an earlier bedtime, or he wouldn't sleep well, would wake super early, and wouldn't nap. It's like the more tired they get, the harder it is for them to sleep. I would move his bedtime up - I think my son was in bed by 7pm at that age - and actually still is in bed by 7:30 at 3 years old.
He could also be hitting a milestone - teething, about to stand, crawl more, so on. He could very well be in pain - being held and rocked can be comforting him so he stops crying. Have you tried an infant painkiller?