Is it just bile or is there food in it? If it's bile, you can try giving her a little bit of food prior to bed; sometimes they just can't handle an empty stomach. If it's containing food, they *can* develop sensitivities to food they have been eating all their lives, but you'd see puking more often and skin stuff to go with it.
You may also try giving some probiotics for a few nights with dinner to reset her GI flora. YOu don't have to do it all the time, but it's good to do every 6 weeks or so. I use a powdered probiotic from nzymes.com, and you can also get good ones at a health food store. I like to get about 4 different strains of bacteria (yogurt doesn't have that many), and add half a capsule. Probiotics are great to have on hand for you as well, so it's not something that will be wasted. You can use it for traveling outside the country or when your tummy feels upset
