I've been having trouble sleeping too and I know how much it sucks.

One thing that hasn't been mentioned yet is exercise -- if you're physically tired, it's sometimes easier to relax mentally. Just don't exercise less than a few hours before you want to go to sleep, or it might have the opposite effect. I know this is easier said than done, but it usually helps me.

Another thing that might help is to have a bedtime routine. You could try giving yourself a certain amount of time to worry about whatever is on your mind (for example, you could write in a journal for fifteen minutes), then do something to help yourself relax (music, warm bath, tea...), then go to bed. If you can't fall asleep after twenty minutes, get up and do something boring for a little while, then go back to bed. Personally, this makes me less anxious about whether I've managed to fall asleep yet when it's some ridiculous hour of the night.

Well, I guess all of this advice is easier said than done, but it's definitely worth a try. Here's a webpage about difficulty falling asleep: How to Sleep Well. I hope you feel better soon.