Shovelnose lobster having problems!

I recently bought a shovelnose lobster, acclimated him at put him in the tank. I got him from the lfs where I work and when these guys came in they were doing great. After a day in the new tank, my lobster is uncoordinated, and spends half of the day on his back. He can't seem to keep his balance and just doesn't seem all there although he is still alive. I checked the water and everything checks out. My only guess is that this guy is getting ready to molt. Any ideas? I use ro water and mix my own salt too.