Sorry to hear this.
No its not always like that,I was diagnosed mm in 2009 april and touch wood have had no hospital stays except May for my stem cell transplant.
I have had a lot of bone pain(plasmacytomas and rib fractures) and tried various meds,morph tablets then mst,oromorph but pain remained nasty so I contacted my macmillen nurse ,who visited and suggested morphine patches ,I had been given these before by consultant but hadnt managed the dose,turns out he put me on 50 !
She worked out how much oromorph daily and tabs i was on and worked out my correct dose and sorted with GP for my prescription.
I still have bone pain but rarely a nasty bone pain day
Is he drinking enough as flank pain can be kidneys but probably is back related (i have prolapsed disk not from mm)
I hope you both get some relax ,comfort home time very soon
best wishes ps great news on the nice PP drop
Suem