I am sorry to hear about your girl's problems.
When doing a brief search for Cymbalta toxicity in dogs, I find that the dose at which signs are first noted is at 20 mg per kg. So, if your dog weighs less than 8 pounds, I would be concerned about her. If she is larger than that, I would likely watch her at home for signs of hyperactivity and neurologic changes like tremoring.
There is no specific antidote for cymbalta in dogs, so if those signs are noted, she should get to your veterinarian to have some supportive measures pursued. In short, if she is less than 8 pounds, I would take her in for observation through the day, and if she is more than that, I would watch her at home and take her in if you see signs.
I hope this helps!
As always, if you have further questions, please don't hesitate to ask them!