I hate to say this? But….

Got Osteoporosis or Osteopenia? That nixes Steroids flat out! That was my case. Also, PP costs more the IVIG per treatment [I believe, at least, in my part of the world] AND while effective it is a more invasive therapy.
Docs usually go into ‘cruise’ mode after getting IVIG approved…But, there have always been ‘standards’ by insurance companies that docs MUST submit updated testing and/or documentation showing improvements of some sort… Albiet, improvment can be deemed ‘not getting worse’.
I wish you luck and keep at it! I realize that it’s exhausting just to even THINK about the fight? But where will you be w/o IVIG? Sounds like your doc is trying [and they’ve got much more experience than you do] to solve this. I truly hope they ‘fix’ it!