hey there. as a physician, I might be able to provide some insight:
metoclopramide is quite commonly used for migraine induced nausea. it's by far the most common reason for me to prescribe it. you should look into and memorize the specific symptoms of aural migraines and bring up with your physician that normal pain medications don't help, so you'd like to try triptans, which are specific migraine medications.
in a little bit, you should follow up with your physician saying that while the meds help with the pain, the nausea itself is really bad. at this point you can bring up metoclopramide yourself, or, if you want to arouse the least suspicion, wait for your physician to suggest it. either way, this to me wouldn't ring any alarm bells. we are trained to be suspicious of certain medications but I can't say metoclopramide is one of them.
I hope this helps a bit. please feel free to PM me if I can do anything else.