I have a sick Platy. Don't know how to help her.?

I have a Platy that is acting weird...she stays at top of tank, is nearly veritical, head up. She is eating, but seems to be getting thin. This is a week in progress. Other community fish are fine, water quality reads excellent. I recently had a neon tetra outbreak that cost me several until I did a 3-day Quick Cure cycle. About 10 days ago. The Platy seemed to improve greatly along with the neons, but she is regressing. Anything I can do?