I don't think it sounds like "your fault" from what you've posted, at least not about the substrate. I'm not convinced she suddenly has an RI, either...
Those lovely photos of her on the ground...are you sure there are no chemicals applied anywhere she might have slithered, grass or flower beds? Personally,
I don't put any of my snakes on the ground, although I know there's no chemicals used on my property, there are other issues to consider, like parasites in the
grass (both internal & external types) or various germs (from stool etc. left by wild creatures) that she could touch or inhale & be infected by. I'm in a similarly
warm & humid state like yours, just a reminder that it's risky, no matter how irresistible & photogenic it is. I do hope she gets well soon.