Thanks! Looking at the DxDiag you sent us it looks like you're using a ROG Gladius II. Do you currently have a specific software installed for that mouse? If so, I'm wondering if there might be an issue with the driver. Since it sounds like your sensitivity is changing constantly it may be something going on with the driver.
When you're able can you try uninstalling and reinstalling the ROG mouse software to see if that helps at all?
/Kent