Go out for a run, exercise, I think you will feel a lot better after, than sitting in front of cRPG for hours =]
Thing is he said it happens after just a half hour or so of playing, and started happening out of nowhere. Sudden onset of motion sickness can be caused by a concussion, tumor, brain swelling, high blood pressure, diabetes..
Typically PC gamer motion sickness (which is common) is from your brain failing to process a different Field of View, you should be setting it to 90 when possible which you can do in game options somewhere, to trick your brain into receiving a more understandable input. Low FoV appears unnaturally zoomed in ahead of where your eyes would be in a FPS, desyncing your brain and causing motion sickness. But this usually happens to people consistently in many games since they start playing, not happening out of nowhere.
Sit further from your screen and mess with FoV and turn off post processing crap. Go to a doctor if it gets worse or happens in another activities.
Peace.
