Is There such a thing as brushing your teeth too much?

Well I went to the dentist last week and was told that I brush my teeth too much. I also have my first cavity. Make sense? I now hate going to the dentist. I use to like going since I would only spend a little time in the chair, and I used to like it when the dentist would say whow nice teeth see you in 6 months. Not no more. I have to brush less and floss more they say. So how did I get my first cavity at 30? I wonder if I even had one to begin with. Now I'm typing this with a frozen jaw. Well I'm off to see my Uncle. Good news Sheri has a new job.
Tam