Just wondering if an "upper gastric motility" class of drug has been tried. Also not to lie down for 30 min to 1 hour after eating or drinking and when tube feeding is given should have upper body elevated at least 30 degrees. These things helped my husband with the nausea related to nutritional intake.
As far as activity goes I think he is on the right track if you can get him to walk a little each day with the goal to increasing the activity each week. Plan any activity with rest periods between. The generalized fatigue can last for quite a long time, up to a year post treatment, so small steps forward are to be appreciated. I think during treatment we are so focused on getting through that phase and are so anxious to be feeling better but do not realize what a slow process it can be. It is not a quick recovery as from surgery. Radiation and chemotherapy are a major assault on the body and require a prolonged recovery period with each person responding differently. All that being said, keep encouraging him, but don't beat yourself up when he doesn't respond to your expectations. No doubt he feels like crap right now but very slowly good days should start to out number the bad. When the anti-depressant kicks in (can take 3-4 weeks) they will also help.
Strength and courage to you both to face the days ahead. We are all here to support you, so visit and vent as often as you need to.