I actually did similar to you not so long ago. I was shot taking 10NL, hit a bit of a down swing, moved back to 5NL and down swing continued. While, after review, I had made a couple of mistakes in some hands a lot of this was just variance (unavoidable spots etc). I couldn't really complain as my win rates at 2 and 5 NL are still huge over a pretty decent sample now.
However, I did become concerned with my roll taking quite a hit and I was struggling to find as many fish as other life commitments had limited the times I was available to play. Although still well rolled for 5NL, I made the decision to sit at the 2NL tables as there seemed to be an abundance of fish sitting with between 1-200bb and making all sorts of spewy errors. I actually regained just over 1/2 of my losses in one 4 table session (admittedly, this dopped up and down as these tables do not fill or remain so as long). I then moved back to 5NL and I am not retaking shots at 10NL.
My point however is I totally agree with 2NL Deep being insanely profitable for a decent player with a solid post-flop game at the micros. In future, should I ever need to, I think I would consider this as a progression from 2NL to 5NL and would recommend others to do so. Although it is important to remember that the game plays differently when this deep.
I would however recommend moving up to 5NL pretty quickly still as, although profitable, these tables play like 2NL tables. A totally different game to 5/10NL and I believe if you stick around there too long you will pick up a lot of bad habits that could cost you dearly 5/10NL.
My advice therefore would be to move back to 5NL, but if you need to drop down again due to a downswing hit the 2NL deep tables instead of the standard 2NL.
What time of day do you play? If you can manage to get the time in at weekends, particularly evenings you can still find crazy fish at 5NL, I have had some insane +$50-60 sessions at these times.