Why is my phones touch misbehaving?

Recently my phone has some sort of touch issues where my display shows i have touched my phones display for a long time instead of a click when i want, it works sometimes for a second properly but the problem starts again.This started a month back, i had these sort of issues before too where i was able to troubleshoot by factory reset however its not working now i have tried restarting phone,cleared cache,factory reset and also i am using the original samsung charger which was provided in the box.The phone is in really good condition(atleast physically). So if anyone can suggest would be great.