Hi, My Baby (almost 14 Months Old) Has Been Very

Hi, My baby (almost 14 months old) has been very fussy for about a week now. He was running a very low grade fever (his is usually 97.3 and it was 99.9) off and on and was very cranky. (He wouldn't let me leave the room.) He also hasn't been wanting to eat for about a week. I know he is cutting more teeth but I was also concerned about an ear infection so I took him to urgent care on Wednesday evening. The doctor confirmed he was teething and also had an ear infection so she prescribed an antibiotic. He has been on that for four days now. My baby doesn't seem to be getting better. Honestly, what concerns me is how lethargic he is acting. He is very active and he has just been laying on the floor throughout the day. (first time he has ever done this!) Do you think I should wait a few more days for medicine to work or should I bring him to his regular pediatrician tomorrow? I am very concerned that something else might be going on...