I'm so sorry you've had to deal with this.
Has your doctor run any tests to find out why you vomited so often with the ostomy and/or why you're so nauseous now? This isn't normal, and you need to find out the cause of this. After having Crohn's for over 20 years, you could have a narrowing of the bowel or an obstruction.
In the meantime, there are a variety of over-the-counter and prescript
ion anti-nausea medicines that you can take to give you some relief, and make sure to drink plenty of fluids, so you don't get dehydrated. Hang in there, and keep us posted on how you're doing.
Dx'd w/ Crohn's in '99 at age 28. Proctocolectomy and ileostomy in '06.
Pain-free, med-free, and very thankful to be healthy again :)