Jeff,
I know how you feel & i went through something similar myself after treatment.
It seems like such an anti-climax! I think it's a combination of things. Through treatment you see someone from your team every day. And then it just stops.
Also, while you're going through treatment you have a goal, something to focus on. & then you're done.
& also... i don't think it really caught up with me until after treament. The enormity of what i'd just been through.
I found convelessing frustrating and difficult. I'd done with treatment so why wasn't my life 'normal' again. I HATED being off work (no thanks to day time telly).
But i can say that feeling does pass. For me it was about 12 weeks post Tx.
Bare with it - you're entitled to feel shell-shocked &/or lousy!

All the best,
Michelle