Whats wrong with my Marble Goby?

Hey guys.. I just noticed my Goby was struggling to swim around, well now it's actually kind of doing the "dying" fish float. I have no idea whats wrong with him and water parameters are fine. It almost looks like it's spine is broke.. look at this pic and you can see what I mean.. granted the waves magnify the curve in it's body but it's still a real significant curve.. what causes this and how do I treat it??

Here are some more pics..

In the tank is another Marble Goby .5" bigger and a striped raphael. Nothing that could have inflected a major wound. It was fine when I bought it, ordered it onine. It's laying on it's side strugling to live.. I'm afraid he's about gone

I don't have anything in the tank that could give it a beating like that. When I woke up this morning it was dead

Nothing.. I checked it all over for scraping or cuts and couldn't find anything.. what exactly is whirling?

Ok, I did a quick google and saw that whirling (which it does resemble) is caused by parasites.. should I treat the tank? I can not lose my last goby.. it would kill me.