I'm pretty sure the problem lies in the headphone jack. I've had the same thing occur to me the past few weeks, whenever i plug in the headphones or earbuds my phone goes crazy, pressing random things and doing random functions. But I've noticed that it only does that with wired headphones, i have Bluetooth connectable ones and whenever i connect none of that happens. So my advice would be to check for any dirt in the headphone jack itself and clean it out with a cotton swab and if that doesn't help then possibly suggest buying wireless headphones or earbuds or bring the phone to a professional who can take a closer look at it.