When do you move down/what do you do?

[JoshuaD]

I'm in the middle of my worst downswing so far in my career of playing.

From the last peak, I'm down about 160BB's playin 5/10 6m, over 5600 hands, spread over 3 or 4 days. It's brutal. My bankroll was at 510BB's before the downswing started.

I was a >2BB winner at this game over about 60k before this downswing.

When do I stop? What's the smartest move?

edit: Make that 170. And I quit for the day.