First of all, it doesn't seem that you have oxygen. That is essential! First priority. Get started on the D3 regimen also, but oxygen is essential. It will stop your attacks and it will reduce your intake of triptans. Too many triptans create big headache problems of their own (medication overuse).
Do the bad symptoms you describe always happen with the spray? Ever with the tablet?? It sounds like you're saying that you typically have enough warning (even "several hours") before an attack that you can go through your progression of tablet/spray/injection. Am I reading that right? And are you also saying that you can sometimes/often lay down as you deal with an attack? And I think you are saying that an injection will stop an attack, but not always since sometimes they go on for three hours or more.
There are a lot of seemingly unusual situations here. I wonder how much triptan you are taking in (the nasal spray is usually zolmitriptan, not sumatriptan). One thing you can/should do is get less than 6mg with your injections. One way to do that is here: https://clusterbusters.org/forums/topic/2446-extending-imitrex/. Another way is to get a prescription for vials and syringes so you can measure your own doses. For most people, 2mg is enough; practically no one needs more than 3.
Many of us here have had physicians brush off symptoms that they don't understand. What you are describing seems serious enough to me that a second opinion seems important. Do you have access to a headache center? They will have seen practically any kind of triptan reaction, I would think, since triptans are prescribed for many "headache" conditions.