Clownfish rapid/isolated behavior

[metree7]

I have had my clownfish for about a month now and he was great, until yesterday. He started hiding out behind a rock and was breathing really fast. It was like he was suspended in that same spot and he didnt want to do anything else. He is still in the same spot today and is still breathing fast. I did all of the tests and it all checks normal. I have had my 55 gal tank for about 7 months. There are no agressors in the tank. I am puzzled. When i fed the tank yesterday, he kind of chased some food but didnt eat anything.