Wanted to chime in with my experience:
I started playing Dragon Age: Inquisition again, and I noticed after a bit that my mouse would jump an extra 90 degrees when panning the camera, or running in a new direction by itself. After a lot of troubleshooting, I managed to fix the issue by addressing two issues:
1) Game was using VSync, and I discovered the game was rather laggy in response to mouse and key entries. Solved by disabling in-game VSync, and forcing Fast Sync via driver profile, in conjunction with RTSS frame capping to maxfps-0.1, which in my case is 59.987. Game is much more responsive, mouse jumping was far less severe, but still happened, which led to...
2) Cleaning my cloth Thermaltake Dasher pad. (To test, I swapped in a Ratpadz) Apparently the residue build-up on the pad was causing tracking issues. Wiped it down with warm water and some dish soap, and a sponge. Let dry overnight. Tracking is solid again.
EDIT: Issue came back. After further testing with other hardware, it turns out it's the game's camera panning.