B.A.
You may have already received this response, but I don't have time to read through everything, and wanted to tell you mine.
This happened with my daughter as well and I was using the dropper method to give her the medicine. When she ran out before she should have I called the pharmacy and they asked immediately if I was using the medicine dropper to administer the medication. I told them I was and she told me that when you use the dropper, that some of the medication gets "wasted" each time, because a little remains in the dropper. The pharmacist gave me an additional amount of the antibiotic so she could continue taking it for the recommended amount of time...