New to Cymbalta

I am just finishing my first week of Cymbalta. My PCP put me on this for chronic left sided headache and neck pain. I had been taking Lexapro for over 12 years for depression. So  my Doctor thought taking Cymbalta would help with the depression and the pain. I have been extremely tired, dry mouth,  and today very, very anxious. I feel like I want to cry for no reason. I have never had any side effects from Lexapro. Can anyone give me and insight n this. Should I keep taking it so that maybe my body can get used to it? 

I will try. I really want this to work for me. I hope that today was just a fluke. I never reacted this way to Lexapro, so I got nervous.
Thank you for the support.

I have been on Cymbalta for quite a few months, and I don't remember having any really significant side effects when I started, but I do remember wondering for weeks and weeks if it was going to do any good, meanwhile crying all the time and just an all around mess. Just like the others here have recommended, my doctor told me to stick it out, and I'm so glad I did. My neuro had started me on a teeny amount of 20 mg which didn't do anything at all. My family doctor increased it to 30, then I went to 60, then 90. It took a while to feel stable but was worth it. Hope you can hang in there!