First of all, amoxicillin is an antibiotic. Doctors prescribe it for bacterial infections. You need not give your daughter amoxicillin for fever or cough unless she has some infections like strep, ear infection etc and the doctor prescribes it for her. And you wont know if she has an infection or not unless she sees the doctor. Why don't you give her some over the counter tylenol/ibuprofen/motrin for fever? If you think it's more than just fever, take her to the doc.
Secondly, If you check the bottle you should see the expiration date. You must use amoxicillin within 14 days after the prescription is filled because the pharmacists mix it with water , so it's good only 14 days after mixing.