I do this sometimes, in waves. When it starts it lasts for weeks, and when it stops, it stops for months, even years. When I notice it, I go to the Walmart or Walgreens and buy these disposable rubber mouth guards and put them in when I start grinding, and before I go to bed. They're $10 and totally worth the price.

They're called "Plackers Grind-No-More" Dental Night Protector Advanced Protection Against Night Time Teeth Grinding. Contains 14 Disposable Units. Individually Packaged And Ready To Use. No Boiling, Cutting, Or Moulding Required.