Tom-
It actually sounds like you are doing well for stage 4 (my wife also has stage 4). From what I have read, those who rank well on the performance scale respond best to treatments, As for the fatigue, how are your blood labs? You could be mildly anemic and if so, that woulf certianly account for the fatigue. My wife gets gemzar which can affect the production of red blood cells, thus causing anemia and fatigue.
Also, you might aks your doctor about a steriod like decadron (works pretty good). One got up one morning only having had 3 1/2 hours of sleep and avery busy day ahead of me and I took a decadron myself (don't tell anyone

and I was amazed at how good, but normal I felt.
However, I am just a private in this army and there are others here who know far more than I. But to answer your question, fatigue and anxiety will accompany stage 4. It took me about 10 weeks, but I finally talked my wife into trying an antidepressant (Lexipro) and it has really helped. I hope you can at some level return to some normal activites such as running. The disease seeks to rob you and your loved ones of more than any of us should conceed. So stay strong and keep the faith.
conan