You poor thing, I went through a period like this with my DS2 too. Sleep deprivation is a terrible thing.

I'm sure they must hit a developmental stage at that age and it throws everything out the window.

I don't really have much advice, the lovely ladies here have given some great tips. The only one I can suggest is if you are co-sleeping - do you wake up when you hear him stir (before he starts crying)? If so, could you try patting him on the tummy (or something else that he likes) as soon as he stirs to help him get through to the next sleep cycle? I did this with DS2 during the day - although I didn't co-sleep, I just snuck in his room a few minutes before his sleep cycle would end - and he eventually worked out how to settle himself back to sleep without any help from me.

I hope this passes really really soon for you.