How to I get my iPhone buttons to work properly?

So I have a iPhone5s only had it for a few months, March to be exact and the side buttons (volume up and down) are very hard to push. Also the one used for the ringer. There isn't any dirt or anything in it or blocking the way but it's jus very hard to use. Anyone know how to fix it besides dealing with Apple.

Those buttons are hardly ever used once set, how they could they suddenly be hard to push?