I had what I thought was breast pain a couple of months ago, but it ended up being a torn pectoral muscle. It hurt pretty bad--they did an ultrasound on my chest and everything to be sure nothing was there (I'm 29). But it ended up being from working out too hard, oops! I had to lay off the upper-body strength training for a couple of weeks, and then it was fine. It is likely nothing because of your age, but it's always good to go get it checked out! (Also, if you've recently gotten on birth control or changed your pills, it could be due to that too--what my doctor told me before we figured out it was muscle-related).
Age has nothing to do with breast cancer! I suggest you go to your doctor and
let the doctor check you and show you how to do a self examination of your breasts. That's not to say you shouldn't go to the doctor for a regular exam.
You ask the doctor how often you should go for examinations.