K.R.
Whenever my 21 month old starts acting up with the sleep routine all of the sudden (a lot of what you've described is exactly what he does) it turns out he has an ear infection. He never shows any of the tell-tale signs (no ear pulling, no fever, no cold, nothing), but I'll take him in and he'll have a raging infection!
My doctor says that with ear infections laying down is painful and the only way we can get our little one to sleep until the meds kick in is having him lay on us or if we hold him in our recliner - so his head is elevated...it may be worth checking out!