Phalaenopsis "Pandora's Box" losing leaves but still has plenty of roots.

[jood]

Hi,
I'm pretty new to growing orchids. I got my first one about 3 years ago and am proud of myself for keeping it alive this long!

I got this second orchid about 8 or 9 months ago. When I bought it it had 2 flower spikes in full bloom. The variety is "Pandora's Box". It's potted in bark chips.

It stopped flowering about 2 months ago. I waited until last week to cut off the flower spikes after they had dried up.


The plant has recently been dropping leaves from the bottom. I have lost a total of 3 leaves and there's no sign of new growth. The 4th leaf looks like it's about to drop any day. It's typical of how the others went, first drooping, then some yellowing close to the main stalk but dropping off before the whole leaf turns yellow.

I thought this might be root rot but it looks like it has plenty of good green roots.

The plant has been fed with diluted plant food probably 4 times since I've had it. It's kept at room temperature at about 18C most of the time. My first orchid (also a phal.) is in the same environment, getting watered at the same time etc. and is thriving so I can't figure out what I'm doing wrong with this one.
I'm in northern Scotland... do you think a lack of light could be the problem?

Thanks for reading.