Newer leaf turning yellow??

[Zekeyflower]

I have an oncidium that I've owned for about a year and a half that has never bloomed since I got it. It is my first and only orchid so at the beginning I wasn't taking care of it correctly. More recently it seemed like it was doing very well.... I found a nice spot for it where it gets a good amount of light and it grew a new psuedo bulb, yay! It is also starting a new growth which I am assuming is going to be another new psuedo bulb. So I finally felt like this plant was thriving.... BUT now it has two yellow leaves. One of them is from an older psuedobulb so I'm not super concerned about it, I think it's just running its natural course. But the other is from the newest psuedobulb and I'm not sure what is going on. I don't feel like I over water them at all. If anything, I under water them. My psuedobulbs tend to get wrinkly and the old ones are super wrinkly. So I don't think it's root rot. So now I'm concerned about the possibility of pests or a disease. I just don't know why a leaf that is less than 1 year old would turn yellow so fast. At the same time, the new growth that is going to be another psuedobulb looks great. Anyone got any ideas what is going on? Please help! I am including pics. First pic is of the oldest leaf that's turned yellow, it had been sunburned it the past so it looks pretty bad. The second is of the new leaf turning yellow. The third is if the new growth. Fourth and fifth pics I included to show the roots. I took these pics after I had just sprayed the roots with water.