problems with guarechea Black Comet

[TER]

Hi,

I have this plant for 3 years and it has been growing and putting on beautiful flowers regularly.

Recently I have noticed some spots on the mature pseudobulbs ( the smallest one has always had it), leaves and pseudobulbs becoming yellowish and it looks like it's spreading. I've unpotted but the roots seemed ok and there is a new growth popping from the potting mix.

The spots make me think that it might be a fungus.

For the yellowing pseudobulbs I am worried that it might be some nutrient deficiency. The tap water I use is hard (7,5 to 8 ph). I use Akerne rain mix twice a month, diluted to a little less than the recommended dosage. I have some other orchids getting yellowish too.

I thought of too much light, but this year is cooler than previous ones with a lot more clouds than normal.

I would like your insights on what might be happening and waht I can do.