Just a suggestion, man, though I don't really know where you're at.

Why not change your game? Either go back to 25 nl, or switch to limit for a while. If you feel like you're evolving, then try out your game in different situations and let it grow. Sharpen your reads, work on your gear-changing, etc. I'm not saying that 50nl is out of your comfort zone, just that moving around might help round things out.

I had a similar experience in the brick&mortar game. After building a nice br playing 10/20 limit, I moved up to 20/40 and burned through most of my br in like 2 weeks of long sessions. I moved around - back to 10/20, big and small nl games, even 5/10 when it looked juicy. Now, I don't even call ahead anymore - I always scope out the tables first and see which game looks best for me.