My phone makes calls by itself send garbled puctuation texts

my phone can be sitting a table by itself and when I look at it, it is calling one of my contacts? when I try to send a text message, it will change to the punctuation screen by itself and then start adding all types of punctuation by itself. its like there is a ghost in my phone. It does the same thing when I am trying to get to a certain screen t will automatically start switching to different screens, so I will set it down and it keeps going by itself.