My iPhone is acting crazy all of a sudden?

Okay so I have an iPhone 5s through Sprint and I don't know why, but it's been acting insane lately. I recently updated to the iOS 9.2.1. I got the phone back in June 2014. I'll click an app multiple times and every time the app crashes. It doesn't matter which app it is (mail, twitter, safari, etc.). Then sometimes it'll randomly vibrate out of no where for like a minute (there's no water damage to the phone and I know it's not because I've received a notification). Sometimes the screen just goes black and stays black regardless of whatever button I press. Apple Music also doesn't work well. I create playlists and songs disappear from them or don't play. I'm honestly ready to throw my phone at the wall.

This is likely to be fixed if you take it to the apple store and ask what's up. Before you do that try re-starting your phone, re inserting the sim card and see if it works.