I'm new on this forum, so I haven't figured out quoting parts of a message yet but I'd guess stress too. You mentioned having your previous dog in your room; if you could do that to reassure him when he wakes you could gradually move his bed, maybe just a couple of feet at a time, to where you...
Have you tried walking backwards and encouraging him towards you? If you have a clicker or marker word You could mark and reward any forward steps. You could progress that to walking sideways then to normal walking forwards.