Dendrobium aggregatum leaf problems

[flyfishdoc]

I won this beautiful den at my first meeting of our local society in April. I put it outside. It bloomed but got too sunburned and I kept it in a south facing window that loses direct sun by 1 or 2. All of the purple has gone, so the light is not too bright now. But even when outside I began to have the black spots on the leaves and the hole opened up. Now I have yellowing leaves and more spots. The newest bulb (which started since I got the plant) is the largest and plumpest. I have many new roots on the surface (I'm not sure how well they show, but they are the white in the medium).
Are the leaves just old and dying? What are the black spots?