What is this line?

What is this line and how do I make it stop? I have tried setting the pressure and such and its on almost every brush I use https://www.dropbox.com/s/y6secnh7qbm7t5y/Screenshot%20from%202016-11-24%2004-41-58.png?dl=0

Its never just a curved tapered line, it always draws this straight line whenever I go to sketch something.