Small orange blisters on Den spectabile

[MrsSky]

Hello,
I am having problems with another dendrobium. It is my large spectabile. I noticed some small orange blisters on new leaves today. I cut them off and sprayed the plant with a sulfur based fungicide. I checked Orchid Species Culture Dendrobium by Baker and Baker and it seems to be a form of rust?
I did let the night temp drop to 60 for 2 nights but it was dry (since this leaves were new and perfect just a few days ago I think that it is the cold). I have had a problem with a black spore fungus since I purchased it. Could the blisters be a part of the the fungus cycle?
I am going to try to read through the pathogen section at the back of the Baker book tonight. Any help is appreciated.