Hi Josie,
I had the same problem with my little man at the same age. Basically I just had to 'bite the bullet' and put him in his cot. I know its hard but it does take a few days to get them used to sleeping in there. Does he sleep in a cot for his day sleeps? Maybe you could try putting his cot in your room for a few weeks and get him used to sleeping in there first before you put him in another room?
I hope something works. Its so distressing I know .