i took cymbalta a few years before my bipolar diagnosis.
i took it for pain as well.

i did really well on cymbalta and only stopped taking it because it was affecting my liver enzymes... (ALAT, ASAT and GGT) i only realise there was something wrong because i was so exhausetd all the time and my bowel movements changed color.
how long have you been taking cymbalta? do you have your liver monitored?
not saying that its your liver but its something to considder...

ETA: duh - 1 month... you said that. sorry.