I HAVE A 17 MONTH OLD YORKIE NAMED DUKE. WHEN HE WAS YOUNGER WE USED TO DRIVE AROUND WITH HIM ALL THE TIME BUT LATELY IVE NOTICED THAT HE BEGINS TO DROOL ALOT AND DOESNT LIKE CAR RIDES ANYMORE. WHAT CAN I DO TO HELP HIM? HOW DO I KNOW IF ITS CARSICKNESS OR IF HES JUST NERVOUS WHEN IT COMES TO CAR RIDES NOW?