Its ‘funny' (ha ha) that you're experiencing jitteriness with cymbalta given it has ‘anti-anxiety' effects (and pain reduction) but according to Drugs.com anxiety is, in fact, a common side effect of this drug. (Go figure). In fact Drugs.com states anxiety is a symptom that you should call your physician and tell him that you're experiencing.
Drugs often have a break-in period that produces symptom flares as your body adjusts to them. Perhaps this is what is happening to you. In any case contact your doctor and tell him/her what you're experiencing.
Good luck with the drug - I hope it works for you.