if it's one of your molars, depending on how old you are, you might not have a cavity and it might just be your wisdom teeth coming in. otherwise, your parents are stupid because they could have put an enamel on them when you were younger to protect your teeth, such as did my parents because i used to get a lot of cavities, which also, if you take care of your teeth, it doesn't really matter if you sneak a bit of sugar. so it could also be sensitive teeth, which i found out was what i had and not cavities, which can be hormonal or happen in someone's life random for a period of time or forever.