Tolumnia Genting Volcano is sick

[cirillonb]

I purchased this Tolumnia Genting Volcano 2 months ago at the grower after it finished blooming for a bargain. At his recommendation I place it in an outer pot with fine bark to provide stability as it was in a tiny pot and wanted to fall over. I also placed some fine bark at the top to stabilize it. At his suggestion I have been watering almost daily by spritzing the surface. Three or 4 spritzes and water is draining out the bottom. The leavea are at least 50% larger than when purchased. However, in the past few days soft brown tips are occurring on a couple.
It was not repotted at the recommendation of the grower.
I feed weekly with DynaGrow and some SuperThrive. I was so proud of it now very worried.
Nick Cirillo