backbulb yellowing/browning, leaves falling

[jellycat]

Hello OB,

I'm here needing your expertise advice again. This one is Laelia ipanema beach.

Problems right now:
The oldest leaf yellowed and fell on 12/9, didn't pay much attention, thought it was normal aging or I pulled it too hard (I tied this one with a disposable chopsticks). Then slowly the 2nd oldest leaf turned yellow and fell today.

I found the browning/yellowing was actually spreading now towards another backbulb, this makes me uneasy. I'm still new to orchids in general but I know this one is cleared from mealybugs/aphids/snails from experience in growing other stuffs.

Some background story:
I got this one on 10/2/21 at a discounted price in a 5"claypot. It was not looking great, medium was broken down, no signs of new growth. Immediately on 10/6/21 I found snails, I decided to repot it in a plastic takeout bowl with wholes I drilled. Medium is Repotme Cattleya mix.

Fast forward in November, it put out 2 new growths, coming with new roots shooting as well. Around the same time I also found some yellowish tiny bugs that looks like spider mites - I was never sure because the plant was looking pretty good. I did treated it twice with some soapy water (Dr. Bronners to be specific). Haven't found them since.

Then it was this month, the new growth kept going. Everything looks great, then this happens.

The pictures:
on DSC08945.jpg (2 of 5):
- the one on the bottom was the oldest, that leaf was gone when I purchased the plant
- then there are those 2 bulbs that the leaves I lost
- and you can also see the browning spreading towards the 4th one.

Is that mold? Maybe it's from the disposable chopstick? I have physon 20 and phyton 27 (that's the cheapest systemic antifungal I can find). Is the phyton 27 gonna help?

Or is that that yellow bugs I ignored? maybe it is spider mite? How can I get rid of that?

Should I be worried at all? Or should I just cut the affected back bulb ASAP?