iPhone 8Plus Clitch

I have been having an ongoing problem with sporadic outbursts of apps opening and closing, text being typed etc. without me touching any buttons on the phone. When I try to close the apps and stop it, it just reopens the apps and overrides what I am trying to do as if there were someone on the back end controlling my phone. None of the updates have seemed to eliminate this problem. It has been ongoing for almost a year now. March 2019 will mark a year that I have had this phone with this problem, in hopes that every update would fix the issue, however; to my disappointment, none of the updates have resolved this ongoing problem.