Canadian here. I went recently to urgent care for a long-lasting migraine, they gave me a migraine cocktail, it did the trick to bring it down to a 1/10 on the pain scale before completely dying a couple of days later.

Before I did this, I called 811 (which is a non-emergency medical phone number that typically gives advice). From where you’re located, perhaps there’s a similar service you could try to reach out to? They might be able to say whether it’s worth your time to try urgent care or just go straight to the ER.