Q: Iphone Touchscreen Not working

So i have an iphone 6 and about a few months ago i noticed something really strange with the touch screen. It would become intermittently unresponsive, it would 'spaz' out when i was scrolling/pinch to zoom/swiping. It would only become back to normal if i would lock then unlock the screen. However, this issue persisted for about 2 days then it stopped. I was like ok not too much of a deal. However, i updated to ios 9 recently then i have noticed this issue even more. In addition my battery started draining really quick and the phone started to heat up atfter just watching some youtube. So i went into the notes app then started to draw some straight lines and low and behold, after about one inch of the line, the line would 'spaz'. I dunno whats wrong with the phone. I have never dropped it in water, never had a crack on my screen and never had any other issues whatsoever. Does anyone have any ideas as to whats happening? Software of hardware? what to do?

P.S. Im starting to think that the conspiracy behing apple slowing down older phones with newer ios updates is becoming more true.