Since about 9 months of age, DS has been sleeping through the night, approx. 12-13 hours. We got in the habit of holding him in our arms to go to sleep, and then transferring him to the crib asleep, but at least he didn't wake up crying for us.

Fast forward to this fall, when he started climbing out of the crib and becoming more independent. We converted the crib to a toddler bed, and his sleep got progressively worse. Lately, he has woken up anywhere from 4-8 times a night, gotten out of bed, and screamed and hit/kicked at the door until we come in to soothe him. If he woke before, he would only cry for a few minutes and put himself back to sleep. The last few nights we have been lying by his bed and patting/shushing him back to sleep. But invariably one of us ends up spending the whole night on the floor, because the wakeups are so frequent.

Any advice, or is this just a phase? He is 21 months.