Andrew,
Please read the post I linked you to. You can fight with your insurance company for O2 and perhaps win -- many have -- or you can get a prescription and pay out of pocket for the O2 without insurance, or you can do as many do and set up a system using welding oxygen. This study, from 10 years ago, met all the criteria for a medical test (randomized, double-blind, placebo-controlled) and showed the effectiveness of O2 for CH: https://jamanetwork.com/journals/jama/fullarticle/185035 Every medical resource about treatment of CH lists O2 as the #1 abortive, along with injected triptans. In short, your insurance company is full of shit. One way or another, YOU NEED O2. IT WILL CHANGE YOUR LIFE.
If you read the previous post I linked you to, you'll see that you can split Imitrex injections (if injections are what you have) and get full relief from much smaller doses.
I don't know why prednisone stops attacks while you're taking it but doesn't end cycles, but that is the common experience. If you're saying you weren't in cycle until after you took the pred, I also have no explanation for that. Often it's used as a bridge to give verapamil time to get into your system. Usually it's administered for more than the few days you mention.
D3. O2. Compensatory strategies as discussed in that other post (e.g., energy shots; melatonin; Benadryl). You need to take control. Not easy to do when you're suffering, but it's what is needed.