Hi - Sorry you and your dad are going through this. I don't claim to be an expert, but in this day and age, he should not have to be in excrutiating pain. Talk to his Dr, there are SO many pain meds out there that there should be something that will work.
My dad was diagnosed in early April with early stage II MM and died the end of May. I don't want to scare you but really the lack of quality of life and very poor decisions by his DR are what caused him to give up.
Best,
Mergie