My son transitioned to a big boy bed last year. He originally loved it, but now that it has time to settle, I think he was scared to get out of it initially because now he will not stay in it. He has been trying to sneak back into our bed and he will even try to sleep in the closet right outside our bedroom door. He has always been snugly sleeper and I think he just doesn't feel the snuggly comfort he craves in his big bed. I thought that by creating a comforting sleep space, then it might help him adjust a little better.
I have heard about the DockATot™ brand for a while now. I knew they had DockATot™ Deluxe which was designed for babies aged 0 to 8 months old or 5-22Ibs. so they can have a safe place to rest, lounge, play, cuddle, do tummy time and even get diaper changes, but they do have a larger version as well. The DockATot Grand is the stage 2 version and it was designed for babies age 9 to 36 months or 22-40lbs. It has been nice having this for him because it seems to be giving him a sense of security that he wasn't feeling before.