What is it:What's wrong with it?

[cirillonb]

I received this unmarked plant as a bonus from an eBay vendor in mid May. It was bare rooted. Looked healthy. I planted it in AussieGold and placed it about 12 inches from an east facing window. All was well until this last week when one leaf yellowed and others looked sick with mottled color. First off...I have no idea of genus (I'm fairly new at this) and secondly...I am concerned about the sudden change in apparent health. I hope I have attached demonstrative pictures.

[CodiMN]

Looks like a dendrobium from here? Pic is kind of far away, but I'm pretty sure I see a cane there.
From what I know, dendrobiums like it a little more dry and like to be snug in their pots.
As for the yellowing leaf, is it a bottom leaf? Orchids sometimes shed leaves over time. They can also shed leaves if they're overwatered.
Let us know a little more about temperature, watering habits, etc.
You did a good job getting those pics up! Keep 'em coming!

[CoolPhrog]

If it is a denrobium, it's not uncommon for them to pout and have an attitude problem after their environment has changed. I had one that was great for a few months and then (after I repotted it) it started getting the spotted and then yellow leaves...dropped quite a few of them. Now it has adjusted and has two new canes coming up...

Patience...careful what you pray for, right?

[Roly0217]

I agree; it looks like a Dendrobium to me and if it is one of the older leaves it's not a big deal make sure to let it dry between waterings and i would downsize the pot. They like to be in a shoe two sizes too small....LOL.

[cirillonb]

Thanks all. I too thought it was a Dendrobium because it did have canes but the leaves were larger than I would have thought (a product of very limited experience.) The roots barely fit into the pot so I don't think I over potted. Appreciate your thoughts. Sorry for the small image.
Nick