Hello! I hope by now you have found a solution to your problem, either by way of fixing or trading up to a different device. It's funny because my mother's galaxy core prime was just acting up this morning - seriously freaking out, opening random applications and touch was near impossible. Upon further tinkering, I have narrowed down her problem to be caused by an after market charger. She forgot her original charger so a borrowed one was used.
Now I am not sure this is directly related to the type of charger, or the software, but unplugging the charger immediately corrected the problem and the device started functioning normally. I then plugged it back in a few times, and every single time the after market charger caused the screen to malfunction, recent app drawer to open repeatedly and left the touch screen impossible to function.
I hope this can help someone narrow things down and help with this crazy random problem! I think we're going to factory reset just to make sure something else isn't causing things to go wrong.
Good luck!