iphone 4 problem

so my iphone4 died from not being charged and so today i charged it and it started messing up heres what happened. it shut off by itself and turned itself on by itself, it told me i had headphones plugged in when i didnt, my volume kept turning itself all the way down by itslf, it wouldnt close when i hit power button, it started calling people for no reason i didnt even have phone with me when it did it it was charging across the room, it started playing itunes music for no reason, it kept asking me if i wanted to shut it down. now it could be cause when i turned my phone on after i charged it i noticed it was wet inside my phone like not soaked kinda looked like the screen was sweaty in my case and mabie it got damaged even tho i didnt go near water. or it could be cause it kinda old