Why is my iphone selecting random apps/buttons on its own and locking me out of my phone?

Why is my iphone selecting random apps/buttons on its own and locking me out of my phone?

My phone has been acting really strange. It's been randomly scrolling and selecting apps and clicking random keys when I try to message someone. Half of the time I can't even open my phone because it won't let me slide up to open it. The same would happen when I tried to restart it, it wouldn't let me slide the power off switch. I'm not sure if the touch screen is broken or if it's some type of virus.