Cymbalta

My doctor started me on Cymbalta 2 days ago. The first day was fine. Today, my arms and calf muscles ached so bad. I was tired. I felt like I had the flu minus the cough and fever. Is this normal? I called my doctor and I never heard back. I don't think im going to take it again.

I've taken antidepressants in the past and never had this as a side effect.

I am also on gabapentin. I know a potential interaction is low sodium.