I think some of it is age development.. My DD was close to that age, and at my wits end as I was only 2 months off having DS took her to sleep school, and that was a nightmare here as well.. I did learn some settling techniques that we still use, but with us there if that makes sense (e.g. the firm voice of lie down and go to sleep, but leaving the room we don't do).

When you say co-sleeping is out of the question, does that involve him being in your room as well? I find if my children are unsettled, just being on the floor on a cot materess (sp?) is enough to give them comfort. I too struggle with co-sleeping from a physical aspect , but DH is fine with them, but he shift works so often not home at night, so I have found ways that work for me.

Hope it is just an age development and he comes out the other side soon.. It is so tough when your little one won't sleep and just seems to cry, but you aren't alone!