Big yellow spots on leaves

[Pupka]

Hi, guys

Thanks for your comments. Overall condition of my phal is okay -- it grows new leaf, roots, and a spike These two leaves are the only concern. I water it once a week, never mist, maybe I should change the fertilizer to a more balanced one, like 20-20-20 maybe? As to spidermites, I never seen them, don't know how they look like. I did notice something similar to a web, on the new young leaf. I'm not even sure if it's a web, it's really tiny and looks like teared apart. Should I continue to spray with fungicide/insecticide?