Small cell lung cancer spread to liver. How to manage the pain after eating? Any ideas?

To cut long story short. Brother has sclc mestasis on liver. Had chemo. Lung doing well but liver cancer back. Sadly not great. He has started chemo to try and shrink cancer to help with pain management. My brother cant eat. When he does exteme pain. Morphine doesnt help. They did mri and cant find anything obvious I.e.bile ducts, gallbladder etc. Also pain worsens when standing too. Oncologist not much help as he cant find why on scan. Does anyone know of this? I've looked on internet but it would suggest bile ducts, gallbladder. He also gets some relief when he lays on his left side. Any advice. Desperate for my poor brother. He has championed so well but this has taken the wheels off for him