iPhone 5c randomly opening and using apps

Ive had my Iphone 5c for a couple years and never had any problems. However recently I've been having some issues with apps seemingly randomly being opened and used. By used meaning that things will be clicked or pressed. For example, once I looked at my phone to see that it had changed apps and gone onto my clock app, gone to the timer and had set a random time and tune. Or I would currently not be playing a game and have it by my side only to come turn on my screen and see multiple things within the game be activated (Such as power ups etc) What's strange is that I've never actually seen it happen. Instead things listed above will only seem to happen when my phone is in my pocket or by my side. Also I don't understand how it could open my phone even though I have a password.

Prior to this, I dropped my phone on a outside stone floor causing the middle of the screen to feel strange and bouncy (Hard to describe). I didn't notice any other issues and even this problem with the screen didn't seem to affect my phone in any major way.

Is there a possibilty that my phone could have been hacked?

Or could it be something to do with my screen being broken?

I just want to find out the problem so I can fix it and ease my mind.

Currently on IOS 9.1

Any help or advice would be appreciated.