Awe, poor Zephyr! I've been checking his blog for updates and was hoping he was healing well.
My guy got really swollen too but my guy also got infected. It's been a couple years ago so I don't remember the timing of it all, but my boy Zane actually ran a fever and had some pus coming from his incisions. I had the vet out again and he gave him antibiotics. Zane was lethargic, so I knew things weren't right.
I had been exercising him per the vet's recommendations and he got an infection anyway.
I believe the swollen sheath is totally normal but at 6 days I would think it should be decreasing by now. Exercise is supposed to help with that along with making sure things are draining properly.
So hmm. I think the main thing would be to keep an eye out for infection. As long as he isn't running a fever or lethargic I would think he is healing up and the swelling will go down eventually.
Poor Zephyr! I love reading his blog. Tell him to get well soon! His fans are counting on him.