Lulu,
I feel for you, it took ages for my daughter to learn to sleep through the night with screaming for hours on end before passing out from being so exhausted.
I remember one night, after about 6-7 sleepless nights I passed out from exhaution while she kept screaming.

I tried behaviour programs but nothing worked, i followed everyones advise but none of that worked. I was told to put her on medication but I didn't like the idea of that. In the end I went to a health food store and got hold of some natural medication to try. Between useing relaxing oils and natural medications she is a lot better than she used to be.

Good Luck

Sjl