Online pharmacy consultation.
I'm in the UK, but it probs still applies... you want to tell the doctor you have moderate pain, left or right sided (localised, no spread) migraine, with vomiting. This is important: it's been of short duration ONLY. (think last 3-5 days). Do not admit to having a history of migraines/recurring migraines or having spoken to a doctor in the past/being treated in the past by a doc for them.
If you take anti-depressants, avoid mentioning them if you can; lack of anti-dep increases odds of meto prescription. If asked about what you've done to control the pain, you can say you've taken OTC stuff like ibuprofen since they've begun. (not long enough for the headache to be caused by med overuse, something they check for).
And say you don't know what's caused the recent migraines, the ibuprofen/OTC med is working OK for the pain, but what you'd like is something to stop the vomiting when it starts as it's interfering with your ability to work. Say you plan to see a doctor should your migraines persist to have it properly investigated. That reassures them.
The biggest mistake you can make is claiming to have a history of migraines. For one, meto is for short term use and they'd prefer you see a doctor to discover the root cause of the head pain and having it treated.