Mouse speed bug

So recently I have decided to bump up my mouse sensitivity up to 90. Everything works for a few minutes and then all of a sudden my mouse seems much slower. I go back to check the settings and its still on 90. The mouse sensitivity refixes itself right when move the mouse speed bar again (either dragging it or even a light click works). Doing that is a short time fix as a couple minutes later into the game, the same problem occurs.