I had a similar experience when moving up to 50nl. But then, I wasn't playing very well at the time. Violent swings can be more common than you think, but it's still worth examining how you were playing the last 3k hands. Have a session review. Post some hands. Otherwise, nobody can tell if you it's normal or not.

If you can't identify a major leak, then I suppose you can just blame the variance and fight through it.