Unfortunately you are experiencing withdrawal from the medication, this withdrawal phase can last around seven days with diarrhea, anxiety as well as your other symptoms. A medical doctor might be able to give you short term medication to help you feel more comfortable but there are no vitamins or supplements that will directly stop your symptoms.
Natural products like Valerian might help with insomnia, and ginger may help with nausea but aside from this, there is no direct alternative to Cymbalta.
Thank you so much for your help.
Happy New Year to you and yours.