Did they check you for h. pylori when they did your endoscopy? That is a bad bacteria that hides in your stomach (it can be hard to find, even with tests) and is the main (maybe even only) cause of stomach ulcers. It can cause vomiting, gas and bad odors. Typically bad odors are caused by a bacterial imbalance, either in the stomach or the intestines, but I think intestinal bad bacteria doesn't usually cause vomiting. You can try probiotics, like acidophillus, as Canyonbabe mentioned, but some bacterias are impossible to overcome without a round (or more) of antibiotics.
There's new breathalyzer test out that can test to see if you have too much or bad bacteria in your intestines (I don't think it can detect h. pylori, though--that's usually found through a sample/biopsy of the stomach lining). That would be something to ask your GI about when you go see him. I think it will also check for overgrowth of yeast, which can not only cause gut problems, but can cause a mild urinary tract infection, which may be why you need to pee so much. A white coating in the mouth (thrush) can be a good indicator of a yeast problem, as can an actual daignosis of a vaginal yeast infection and/or a UTI. (They're finding that where you have one yeast infection, you frequently can have two--i.e. also in the intestines).
And make sure to let your doctor(s) know if you have 1) been to any foreign country anytime before becoming ill; 2) if you have drank from an unfiltered water source (such as a spring, creek or a well that's not been quality tested in a while) prior to becoming ill; 3) work on an animal farm, or vet's office, or otherwise come in contact with a lot of animals (and their wastes) frequently. All of these things can lead to a stomach/intestinal parasite or bacteria that can give you vomiting and your other symptoms.
The other thing to check for in this day and age is e.coli. I think that is typically combined with excessive diarrhea, but Crohn's is also typically associated with diarrhea, but there is a small percentage of people who suffer from constipation because of it, so you can never be too sure with gut problems. Let your doctor know if you eat a lot of organic produce that you (or a family member) doens't grow. The last outbreak or two of e.coli and other bad bacterias was more prevelant in organic produce because they are more likely to use animal waste as a natural fertilizer and are less likely to use chemicals to wash the plants off.