Problem with camera-focus stuck on bottom (iPhone 4S)

Hello

Since last week my camera can't focus correctly for some reason. It's always stuck on the bottom part (and on the side in landscape mode).

When I tap other parts of the screen it seems to adjust but just goes back to focusing the bottom. I tried a long tap that stops the autofocus-doesn't work.

Running iOS 6.1 on 4S.

Any suggestions for a solution?

Thank you!