Oh Bel - that sounds just like Anyssa a week ago. She is much better now, so hopefully Luke will also improve again soon.
I was seriously stressed out with her when she wasn't sleeping - in the end I started rocking her to sleep, letting her sleep on my chest, and going for a walk in the buggy to make sure she got some sleep each day.
I posted a thread called "sleeping woes" which is now on page 3 - people had some good advice there, so you might like to have a wee flick thru that.
Fingers crossed he will just get better again...Take care