Can anything be done for my sea star?

[christinaecampb]

My formerly active Red Knobby Sea Star has been extremely droopy-looking for the past three days. I put him in a QT. Doing daily water changes. He sits on the side of the glass near the top by the overflow with his legs partially drooping off the glass.

Here are my questions:
1) What should I feed him when he is alone in a tank with no live rock?

2) What can I do to help him regain his vibrance? Does he need medication?