It might only be something as banal as changing the width or the length of the strap. And I dare not say it, but TBirds are not the most ergonomic creation on earth, tough it's difficult imagining you of all people playing anything else.
Do consider changing to ballerinas before giving up performing!
Flats, doubt that, heels do wonders for my legs
The Birds are pretty comfy for me and I keep my strap length a bit short, as for me that feels better. The reality of it is that most bands do not play for 3 hours at a furious pace, and it's not too surprising that I'm having issues considering my age. The Nasty Habits has been around for 20 years, which, for a cover band is pretty good, we'll play 2-3 more years and I'll retire from it, a decision that I'm at peace with. It'll be time to move on to other things in life, I want to travel more and quite simply, enjoy life with my husband, he's been patient and very supportive of me for far too long.