They are these little mini oxygen things that are made for hikers. They are semi effective, but after reading what everyone wrote about the welding o2 or going to a medical supply, I am going to go that route. I didnt know about these things because anytime I have asked for o2 from a doctor they have not allowed me to get it. So I thought those mini oxygen tanks were my only option.
For me, the cycle begins slow, like 1 every 2 or 3 days. Then it moves to 1 every day. At the peak of my cycle I am at 3 a day and then suddenly they stop. Mine don't taper off, they just stop. What I can say is that if you are in your peak part of the cycle, it is orobably on its way out. Also try and remember how long this cycle lasts, as well as, how long previous cycles may have been. My cycle is about 6 weeks, I'm at week 4 rn, so I should be ending soon. But I just keep track of time.
As for Oxygen, you just need a Rx. Ask Dr. for it and a good respiratory/medical supply place and pay out of pocket, its super cheap ( mine are 7 bucks a tank, good for 4 headaches)..It is so worth it.