Grinding her teeth

Is anyone else's LO doing this?  DD just started this over the past week.  Her 2 bottom teeth came in at 4 months and now at 7.5 months we have 4 more coming in at once and she's started grinding.  It's the worst noise ever, like nails on a chalkboard.  I try to pop a teether in her mouth when she's awake but she does it in her sleep too.  I'm cringing just thinking about it!!