My 4 years son has an ear pain for more than 3 hours, he also has cold and cough... could you please advise if we can take amoxicillin ear drops?

No: There is no such thing as Amoxicillin ear drops. Amoxicillin is an oral antibiotic. It is not unusual to get ear pain with an upper respiratory infection. Check for fever. Generally ear pain will resolve within 24 hours. Give him a pain reliever. If he starts running high fevers or pain does not resolve, than call his doctor to be seen.