Insomnia

I'm not sure why, but I've been having trouble getting to sleep the past couple weeks. I'll feel tired, head to bed, and once my head hits the pillow, thoughts start running through my mind that I can't seem to turn off. The first night was the night after K was sick and vomited last week, then the night after that I had trouble getting to sleep because I was worried she'd sleep poorly. Then the night after that I was worried I wouldn't be able to sleep and would be even more tired at work the next day, and also had a bout of vomiting and diarrhea myself. The next night I was on call, but had a good 7 hours of uninterrupted sleep in the hospital, which was fabulous.
We went on a 5 hour road trip to see my brother and his family for the weekend, and K was a trooper through the trip. On the way down, she vomited up 2 full bottles of milk all over herself and her carseat, which made the rest of the trip somewhat fragrant. I'm not sure if it was something leftover from Monday's vomiting, or if she's maybe getting carsick. At any rate, she slept great in a pack 'n play for the weekend, and I had a couple good nights of sleep on the pull-out couch.
Once back at home, the bad sleep was unfortunately back. I've had a couple nights where I've taken a sleeping pill, and then worried it wasn't going to work, or that I wouldn't hear K crying if I took it.
Now it's becoming a vicious circle. I'm tired, but I worry I won't get to sleep, so the adrenalin starts pumping and I get more awake, and then lie there for ages staring at the clock and thinking about the sleep I'm missing out on and just get more and more wound up. And each night I sleep poorly, I put more pressure on myself, thinking that I need to finally get a good night's sleep or I'll be screwed.
I think I'm going to have to start doing some of the non-medication things to promote good sleep. Like getting out of bed again after 20min of not falling asleep to do something quiet till I'm tired and ready to try again. And not napping after 3pm, and going to bed and getting up at the same time each day, whether it's the weekend or not. Deep breathing, guided imagery, all that stuff.
Have any of you had to deal with insomnia and overcome it? Help!