Why does the music on my iPhone 4S crash?

Okay so I open my camera (no, it is NOT on video setting, I know the music fades when the video is on) and it just crashes. I have an iPhone 4S, and lately it's been laggy and crashing. Can anyone please help me? It's driving me crazy! Also, it just sometimes crashes all of the sudden. I have turned off the Facebook from your phone thing, because I read that it makes your phone messed up. I delete apps running in the background every time I'm done on my phone for a while. Please please help.
~Holly Rae

You may be behind on your updates- if you go to Settings and there's a 1 on the general tab, click General and go to software update and install update. If that doesn't work, try double clicking the home button and holding down on one of the apps until it has a minus sign in the corner.tap that and keep tapping it on all the other apps until there aren't any more. This is basically clearing your app history, and usually makes any internet-using apps run faster.