Phalaenopsis yellow leaf spots

[Busygirl]

Hello all, I'm new to this fabulous forum. I've been in love with Orchids severely for over a year or so, accumulating a large collection. I have much to learn.

I need help diagnosing my first Phal, she's been around for 4 or 5 years now. But I'm worried she's sick! I think it's a micro fungal disease. With that said, I'm trying to purchase the proper fungicides. I planned to try Alan Koch of Gold Country Orchids advice, using Thiomyl first. (I don't have Banrot, & planned to substitute with Thiomyl brand). Which Alitte to buy? .. (only place I've found to purchase it at is Amazon) and what would be the right Subdue fungicide?

Thank you in advance for suggestions and advice.