Bone pain is very common post STC, but is manageable if you get on the correct pain relief regime. Tell your medical team about the pain you are in and the difficulties you are having. Be aware though that if you also have kidney disease as a result of the Myeloma, some drugs (such as Oramorph and Ibrufen) can be harmful to them, but the good news is that there are alternatives that are not harmful, but not routinely prescribed unless there is a need.
Regards, Tony