sleep regression, teething or separation anxiety?

Amanda • Michael Joseph 7-17-16
My 10 1/2 month old son has been waking multiple times in the middle of the night for over a month now crying. Almost every time he stands up in his crib and just cries. We tried to let him cry it out and see if he could just lay down and go back to sleep but he doesn't know how to lay himself down, he can only sit himself down.  So we have to go in his room every time and lay him down. It's starting to get pretty bad to the point he was awake an hour and a half last night crying off and on.  He's always slept through the night so I'm pretty sure it's not because he wants a bottle. Someone please tell me this is just a phase... and it's not gonna last much longer