Firstly, how big a sample size do you have for the $6.50s? Were you consistantly beating them over say 1000 games?
I don't have much experience at $10s myself but I believe there is quite a large jump in the amount of regs in those games compared to the $5s/$6s.
Your sample size is very small so far, but if you're thinking about your bankroll when playing I would move back down and rebuild. The last thing you want is it to negatively affect how you play.
I am bonus whoring using sngs at the moment. Over the last 3 sites I've played ~1,500 $1,20 and $3,30 sngs averaging ~10% ROI. I just moved to a new one and over 75ish games I'm -20%. The variance is huge and I know I'm not a -20% player. I'm properly rolled so the downswing isn't really bothering me. Who knows how long it will last.
I think the best thing you can do is drop down and get your confidence back, then hit the $10s hard again.