Strange touchscreen issue with my phone

[Shammikit]

I have an HTC U Play which is around 3 years old now (as i remember) and Im having this touchscreen issue with it where sometimes its taking the inputs from the wrong places of the screen, sometimes it swipes back on forth between pages on its own and sometimes it doesnt take any input at all. The reason I say its strange is because I have never dropped this phone, so I can ensure theres no physical damage atleast. And the issue goes away when I press the power button and unlock it again, sometimes goes away for few hours, sometimes for a couple of minutes and sometimes it doesnt fix at all. Sometimes the phone requires one or more restarts to get the touchscreen to respond properly again. I thought something from the software side was corrupted so I reset the phone and with no apps installed, it still had the issue. I tried updating the phone as well and that didnt help either. I also noticed that the Issue has a greater tendency of happening when trying to use the phone while plugged into the charger. What could be the problem? Is the touchscreen in my phone giving away?