My Almost 4 Year Old Was Given Amoxicillin Today For

My almost 4 year old was given amoxicillin today for bronchitis. I only got about 2ml of the first 5ml dose into him as he fought me. Instructions were to give him 5mls twice daily. I have done some research and it seems antibiotics may not even be necessary to treat bronchitis. He has no other health conditions. He is comfortable after tylenol but not too happy when it wears off. He is coughing, congested and has a fever that comes and goes of about 101/102. I know not to stop antibiotics early but wonder if that still applies in this case if only half a dose was given. Thanks.