I have a simple cyst on my left ovary size is 6x4, i had a transvag u/s 2 weeks ago and still have severe pain did vomit once could it have burst?

Yes, go to ER!: I'm so sorry you're going through this. Definitely it could still be there, or it could have ruptured, either is possible. Pain and vomiting can also be a sign of ovarian torsion.... Which is something that needs immediate surgical attention. I recommend that you go to the er for evaluation now... In the event that you have this condition your doctors need to know. Best of luck to you!