Phal and oncidium leaf spots identification

[shadowteme]

Hi everyone!

I need some help again I have three orchids with spotting/discoloration on their leaves (two phals and one oncidium type, all of them no ID), and the ones on the two phals are especially concerning to me. Some disease or fungal infection has recently killed a phal in a matter of days, and even though these spots look a bit different, they are spreading and I can't help but worry. They did share space and the small phal also shared water with this sick orchid before I noticed and started using separate containers.

Big phal:


Mini phal:


Oncidium:


There are no pests on any of them, no webbing no nothing. My growing conditions are on the dry side with 50% humidity, temperatures now ranging between 23-20°C. I water with rain water once a week and I never spray my orchids because I’m paranoid about causing crown rot.

Any advice/input is appreciated!