Any Peppered Cory Cat Experts?

Okay, so I just bought a tiny peppered cory cat at Petsmart yesterday, and today, when I looked in the tank he was floating close to the filter! He is floating on his sides and his eyes are bullgy. I scooped him up in a dixie cup thiking he was dead and he turnined on his stomch and wriggled a bit. I put his in a old cleaned out coolwhip bowl with a frozen blodworm cunck. When I blow, he turns on his stomache an d wiggled. What should I do???