Hi! Don't worry! This happens. It's called "vapor's tongue" and almost everyone has experienced it! You can try brushing teeth/tongue, sniffing ground coffee, tasting something strong / acidic like pickle juice, lemon juice, etc., just waiting it out (it will pass), vaping unflavored e liquid for a little while.
It just happens sometimes. Often it happens if you vape the same juice for too long, so it can help to switch between flavors, but I vape around 10 different flavors every day, and it still occasionally happens to me!
Generally it's a good idea to drink a lot of water while vaping, because vaping can dehydrate you a bit, and it also may help keep vapor's tongue away, but it can still happen even if you're fully hydrated.
Don't worry. It will pass. A lot of people take this opportunity to vape the juices they don't care for that much, since they won't be tasting it anyway.