Sister Jen recently posted here about Cam being stressed out before school. I've gone through this once or twice with Jacelyn, especially when she's wound up because there are people at the house, or her daddy is home, or whatever. Our secret? Massage. We read a story or two (currently 'Hop on Pop' and 'The Grinch Meets His Max' are on heaviest rotation, although she's also very fond of 'If Cats and Dogs Were Dinosaurs'), say goodnight, then I turn off the light, bust out the lavender baby lotion, and give her a good rub down. She giggles like a fiend sometimes, sometimes she just says "Yeah, yeah, that's good, mommy". Either way, by the time we're done, she's a limp little monkey and ready to go off to sleep. Although I am having to use 'mommy's magic sleep egg', an imaginary egg with sleepy goo inside that I break on top of her head, and then run my fingers down her face like the sleepy goo. Very scientific.
That's my only suggestion, and that works for us, but different strokes for different folks. Peppermint is supposed to be helpful for stomach ailments, maybe try it one night with some peppermint oil or lotion? Good luck!