My doctor prescribed me Maxalt 5mg tablets rizatriptan.
It has been effective in abort CH attacks until now but only have 2 more pills and the prescrition I had to left in the pharmacy.
My GP only give consults at Thursday and Friday and I am waiting to give him the form to get oxigen.
What I can do?

Call his office and ask for any pharmaceutical samples they might have to get you through. If they have none, insist on being seen sooner. If they won't, you're going to have to step up your game and go after some welding O2.

If you were receiving the medicine under insurance (in the U.S.), then you have the right to petition the insurance company for a greater amount. You will need to have your doctor fill out some kind of form stating that you need higher quantities due to your unique medical condition.

Make no mistake, a majority of insurers will make this at least a minor hassle for you. But be persistent! You may even be pleasantly surprised. All it took was one letter from my neuro and I went from "only 4 boxes of 'trex" per month to "13 boxes". I'm sure they hate paying out $3000 worth of meds to me per month but... tough nuts for them!  ;D And good luck.