If the leaves stopped yellowing once it was repotted, I wonder if it dropped the flowers and spike to recover. Flowering takes a lot of energy, and if it needs to recover from root rot, it would make sense to drop the spike first. Watering once in 6 days, especially with a bark medium, does not seem to me to constitute overwatering.
I've never had to spray for mites, so I don't have any advice on that. I'm sure others do. Good luck!
