Since you had an ultrasound, did the doctor set you up with a follow up appt to discuss the results? If not, you need to do that and go from there. Good luck!
The only bit I'm clear on is the "appears to be very vascular" this means that there is a blood supply to the mass. I would make an appointment with a gynocologist who will likley refer you to a gyn/oncologist. They will be able to explain the results of the sonogram more thoroughly and advise you of your next steps