The back of my iphone 4 looks blurry when taking pictures, Why?

I have an iphone 4 had it for awhile but about a week ago the back camera is blurry. I've had this happen before but it looked like there was steam in the camera lens and I let that air out and it went back to normal. So whats the problem this time? My mom isn't willing to buy me another iphone because before I went to a concert and the speakers messed up half the screen. If its the software acting up can I get a free new one?

If there is water in it, put it in rice to drain it all out. If that doesn't fix it, take it to the apple store