Small dark spots on Dendrobium Phalaenopsis leaves

[Jlin]

Here’s a follow up on this - the plant quickly declined in a week and the leaves started to yellow and rot. I covered the whole plant in cinnamon until I could buy a fungicide I found locally, and sprayed the plant down. I cut the affected leaves.
Another Dendrobium got affected by something on the leaves and I sprayed it too.

Not sure what’s it is but I will be careful. Any advice appreciated!