Is he learning something new, like sitting up? A lot of times they are so eager to practice they just can't sleep. I've also heard that babies do this when they are about to have a significant change, like sitting up, crawling, etc. It could possibly be teething. It could be a growth spurt and he's just getting hungry. Maybe he just wants to be close to you.
We've all been there and it does stop! Just never as soon as you'd like it to. Another suggestion that you swaddle your baby in a t-shirt that you've been wearing so they can still smell you. I used to do this with my daughter - tuck in one of my t-shirts between the folds of her blanket (so she could smell me, but it wasn't loose, of course, she was still really little).
Anyway, not much advice, but know it will pass. Just keep doing the same routine you've always done everynight and it will get better.