Cattleya walkeriana with black spots on leaves

[Jasonmc89]

Hi there, I've had a Cattleya walkeriana for a few months now and it seems do be doing okay. It's been putting out nice healthy roots over the last couple of months and most of the pseudobulbs are nice, fat and smooth. The plant is on a west facing window ledge, planted in medium bark, in a 9cm clay pot with 1cm holes all around it. I water the plant when the potting mix becomes just dry by sitting it in room temperature water up to pot level for about 10 minutes. I feed every other watering. I also have a small fan in the area circulating the air, but not blowing the plant directly.

The black spots started to show up a couple of weeks ago on one leaf and grew quite fast. I decided to remove the leaf with a sterilised craft knife and covered the cut area with cinnamon. Since then another couple of leaves seem to be getting the same black spots.

The spots don't seem mushy or watery but are a little sunken and they are a dark blackish purple colour. I'm pretty sure it's not sunburn as it's winter at the moment and it's pretty dull and cloudy. It's not cold though.

Does this sound like classic black spot or could it be something else? I have attached a photo.

Any help would be greatly appreciated!

Cheers.