bloated

OK SO MY GOLDFISH HAS BEEN LIKE THIS FOR A WEEK OR SO HIS SIDES ARE BLOATED AND HE STAYS AT THE BOTTOM OF THE TANK OCCASIONALLY GOING TO THE TOP FOR AIR I THINK AND THEN FLOATS DOWN TO THE BOTTOM AGAIN. HE HASNT EATEN FOR A WEEK AND HIS UNDERSIDE AND EDGE OF HIS FINS ARE TURNING WHITE. HE IS...