SOLUTION!!!
If you read the links that DVBourassa has posted, it will lead you to an article for a potential cure. I would definitely try this. I have copy and pasted the link below plus the pertinent information to resolve this issue...
http://www.finchniche.com/f-twirling2.mgi
"So I treated the BIRDS with NYSTATIN 100,000 U SUSPENSION, 5 drops per 1 oz. water. Nystatin is usually administered directly into the bird’s beak at 1 drop twice daily, but I didn't want to stress out the bird by catching & handling him."
This guy is claiming 4 successes. 3 of them were upon immediately noticing this problem, one of them was after months of the onset of stargazing/whirling. In that case, the response took some time, not a day or 2 like the other 3.
I hope you try this method. Please keep us posted on this situation I would love to see a happy ending to this!