Could it be the pregnancy making you vomit?
I have had problems with nausea and vomiting from time to time. Usually I'll just throw up once and then feel fine. I haven't had any pain with it though. If you're having pain with it also, you may want to get it checked out further, just to be safe. The ER can't do a CT or xrays (well, they can, but that's another discussion) but you can have an MRI done. They also can give you fluids to keep you from getting dehydrated.
If you don't go to the ER, ean you call your GI and insist they make an appointment to see you? That way you would at least be seen by a dr to see if they think it's just CD related.
31 yr old female-dx with Crohn's in '97 after emergency resection and appendectomy, 2nd resection '05, Bilateral pulmonary emboli 10/09
Currently on Humira, Omeprazole, Effexor, Seroquel, Calcium, Vit D, sublingual B12, Coumadin