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?

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!  And good luck.