Sterla, you may have tried some of these things already but I just thought I'd ramble off the suggestions I've got in my head. Disregard them if you've already been there, done that!

Do you wrap him? Would that keep him more snug and secure IYKWIM?

What is he sleeping in? Cot, bassinet, cradle etc? Would he be feeling overwhelmed and nervous in a big cot and maybe thats waking him? When DS was born, my sister gave me a cuddlecot mattress, its a wool mattress to fit a bassinet but its actually mildly contoured, so DS gets a little snug spot in the middle with some shape around him, and feels a bit more secure I think.

Is there something in his room that could be distracting him? Maybe try and see things from his physical point of view and try and figure out if something might be worrying him.

I hope you get some more restful nights hun, good luck.