Hi Donna,
I believe yout father's confusion can be related to very high calcium levels – hence the medical team trying to reduce the levels.
I think the same as Michelle re the second opinion. There are 'other things', perhaps less widely used that can and are being used. I know someone else who didn't respond to the standard treatments and was put on one of these (sorry I can't remember what it was).
Calling the Myeloma help line has been a great help to me. They're very easy to talk to and give great advice.
Hoping the best for you and your Dad.
Jim