try different flavors of toothpaste, or just brush with water. Toothpaste is really just needed to help keep calculus to a minimum if you tend to build up fast and protect you from cavities (as long as it contains flouride). So as long as you can atleast get some brushing with just water, that should get the plaque off the gumline, and then try some floss to get everything clean between your teeth, you should be okay. I am a dental hygienist and even I am having trouble brushing and flossing, so just do the best you can without making yourself vomit. And if you do vomit do not brush your teeth for 20 minutes, just rinse with water right away and hold off on brushing so that the acid from vomiting doesn't wear away your enamel (which can happen if you brush right away)