2002 Cadillac Deville SMELLS AND WHITE SMOKE

HELLO I JUST RECENTLY BROUGHT THE CAR LISTED ABOVE FROM A PRIVATE OWNER. I HAD A OIL CHANGE, CATALSYT CONVERTOR REPLACED, A BELT REPLACED (CANT THINK OF THE NAME). IN THE LAST THREE WEEKS. MY CAR SOMETIMES HAVE A SMELL IN THE MORNING AND WHEN I COME OUT IN THE MORNING THERE IS A LOT OF WHITE SOME WHILE I AM WARMING THE CAR. SHOULD I NOT TURN THE HEAT ON UNTIL MAYBE A FEW MINUTES LATER. THE SMOKE CLEARS AFTER A WHILE BUT SHOULD IT BE SO MUCH SMOKE. THERE ARE TWO PIPES IN THE BACK. SOMETIMES I SMELL THE ROTTEN EGG SMELL BUT I JUST GOT A NEW CONVERTOR. MY COMPUTER SAYS CHECK COOLANT LEVEL BUT I TOOK IT TO THE SHOP AND THEY SAID IT WAS FULL.