Kidney stones can cause nausea. Are you also having pain in your back, just under your rib cage? Any blood in your urine?
What are your doctors doing? They saw "something" on the scan, which they thought MIGHT be a stone.........are they having you screen your urine to see if you are passing any stones? What is their plan? Did you tell them about the vomiting? If not, I would suggest you do so as soon as possible. Vomiting for that long can induce severe dehydration, which is something you should not take lightly. It can also cause damage to your esophagus from the stomach acid.
Vomiting for no apparent reason, except a slight possibility that it's stress induced, or for more than a few days, needs to be brought to the attention of your doctors.
I urge you strongly to see a doctor very soon.
Rumination syndrome could possibly be the issue. You can see the details here:http://en.wikipedia.org/wiki/Rumination_syndrome . Even if you may be a perfectly normal adult, and even though this disorder is most common in infants and mentally disabled people, this condition is now becoming more common among healthy and able adolescents/adults. I have been diagnosed with this condition after experiencing a year of bulimia, and although you may not have had an eating disorder, rumination syndrome can be associated with anxiety and stress. You should ask your doctor about this because it is usually easily treated with therapy and biofeedback and does not need expensive tests to diagnose it. Just thought i'd throw it out there because this disease is swept under the rug in a lot of circumstances.