I hope the diverticulitis will respond to treatment. I know two people who suffer with it and it really is awful. Medical tests are stressful too, which doesn't help pain conditions. Will say a prayer for you on the 11th.
I'm like you, frustrated with the lack of progress with the knee, I don't think there's anything intrinsically wrong with it, just the soft tissues taking ages to heal, or the RA flaring up. Still don't think everything I've been through in the last 5 months is worth it yet, but I couldn't go on like I was.
Hoping for better things for the both of us.
Love 'n hugs,