Elrik',
As ThatHurtsMyHead had suspected, this is the wrong mask. Non-rebreather, as you say, is what you want. Your oxygen supplier should have one. A basic one is about quite inexpensive at amazon. For example: https://www.amazon.com/Dealmed-Non-Rebreather-Oxygen-Mask-Adult/dp/B079HDP62H/ref=sr_1_3_a_it?ie=UTF8&qid=1544374018&sr=8-3&keywords=nonrebreather%2Boxygen%2Bmask&th=1
There is probably a way to adapt your current mask, but I'm not clever enough to know what it would be. This is a link to the mask made specifically for CH, which people have very good experiences with: http://www.clusterheadaches.com/ccp8/index.php?app=ecom&ns=prodshow&ref=clustero2kit
With a tank and a regulator that goes to 15 as yours does, you should be able to get success with the right mask.
I know there are Omega-3 pills made for vegetarians. It's possible that Batch has advice related to the most desirable EPA/DHA amounts and ratio. In his post, Batch is saying that the 5,000IU/day of D3 you are/were taking is not enough to get your D level high enough, and even 10,000IU/day will take a long time. He's encouraging you to do the 50,000IU/day "loading" regimen (and to be sure you take all the other ingredients).
Jaw pain is not uncommon with CH.
It's slightly troubling to me that a sumatriptan injection doesn't stop an attack for you. Maybe that happens with some people with CH, but I'm sure it's very rare. Important information for your neurologist appointment.