Suggest Treatment For An Ear Infection While On Ampicillin

My 12 y.o. son had an ear infection that began 12 days ago. He was treated with antibiotics - Ampicillin - and his last dose was yesterday. 7 days ago, he spiked a temp of 101.3, but the following morning it was in the 99 range and the next day it was normal. He has felt fine since. This afternoon, he said he was feeling a bit off, so he rested. His appetite is fine. He s been holding his head tilted back and when I asked him about it, he said that it feels a little weird in front. He said he noticed it when I checked the tag in the neck of his shirt to see what size it was. He s afraid he hurt the blood vessels in his neck, but he also says he s not in any pain and his temp is fine. He sounds genuinely afraid that something is wrong. This behavior is completely aberrant for him. I m conflicted as to whether I should bring him to an ER or see if he can sleep and see how it is in the morning. Any thoughts would be appreciated.