Back Pain (left side) from Liver ?

We have been going along ok, but my husband has developed back pain on his left side.
Had a CT Scan and we are waiting for results. The onc. did say there was no cancer spread to the bones and wasn't anything showing up at the location of the pain. The onc. said it could be a chemical problem (potassium or magnesium) or tumor on liver could be pressing on diaphragm?

Anyone had any similar experiences?

Thanks for your help