My mom has small cell lung cancer metastacised to her liver and she has had her ups and downs, good days and bad days. What has helped her get more energy in the past are these things:
Steroids (always tend to give her energy and appetite)
Getting on the right nausea meds. She has found relief from IV Phenergan when the nausea is overhwhelming, and of course they can do that in the oncologist office. Other things that have helped include Compazine, Scopolamine patches (the ones you use for cruises), Sea Bands on the wrist, and Decadron.
Taking enough pain meds. My mom uses a long acting pain reliever (Morphine) and Dilaudid for breakthrough pain. Once they found the right dosage of Morphine (one time every twelve hours), not as much Dilaudid was needed. Dilaudid tended to make her confused and very tired.
Finding different things to eat. Laughing cow cheese on triscuit crackers was a good one. Sliced Granny apples for the fresh sour taste. Frozen TGI Fridays potato skins from the grocery with sour cream. Salt and vinegar chips. Popsicles. I did find that if she ate well one day, the next day was usually one of her good days. Prescribing Megase to increase appetite might help.
Hope something in this info gives relief and more energy.
Laura