Plutonium

So I haven't played in a while, but when I went to play tonight, I realized my sensitivity was being weird. I tried changing fov scale, fov, and my sensitivity, and even restoring settings to default but nothing fixed it. Whats happening is that when ever I just turn whether aimed in or not, it is a normal sensitivity, then it either slows down or speeds up, and basically " chops " around. Its very unstable and I'm looking for a fix.