Probably because of those NW's! He's probably shattered come morning! I hate the 4mo SR, it was definitely one of the worse for us.
There is a pretty massive GS around now too which many have found introduction of another NF helps for the time being. If bottle fed, make sure he's got at least 1-2oz left over in it so he's not finishing because he's run out iykwim. If BF, unfortunately there's not much you can do either, just accept the extra NF for the time being.
All I can suggest is be consistent. Stick to your ground rules. If you're completely against something like co-sleeping or rocking, just don't do it. Stay with ssh/pat or feeding (if longer than 3-4hrs since last feed) and just try and get through it. You will, it's just a phase but it's pretty yucky for the time being.
I'm not so great with the dummy though I'm afraid. I have read on here some prefer to go cold turkey, but that might be best for another post when you get back after Xmas and you can ask that of more experienced mummas! Sorry xx