The Lightfoot song works well--that's great.   Is the rest of your material mainly Dylan or Dylan-like songs?    That may not be that easy on the voice.   Maybe you want to bring in more melodious songs--like the Lightfoot--and less Dylan-like stuff.

Also, is it possible there is something in your venue which is not good for the voice--like smoke--or something else?

One more thing.   My voice has sunk--now I can be a second bass--which is great. I can hit low E's and D's--and even below that--for the first time ever.   And I've kept the higher notes (through a strong falsetto--thanks to the Beach Boys.)   If you're still doing the same songs you've done for decades--in the same keys--maybe your voice has also sunk. So all you'd have to do is change the key you do some songs in and you'll be fine.