I wouldn't finish it. If you are concerned, call your local pharmacist, let him know what happened, he should be able to help you.
I would finish the course.
Cipro is a fluoroqinalone, and is not the best choice for an intestinal infection. Ordinary over-the-counter pepto bismal would have been more appropriate. Bismuth is a powerful bactricidal agent.
Cipro has many side effects and was not an appropriate. In Mexico, what is labled "Cipro" could be anything from powdered dog dung to flour and insecticide.