2 month old fever, ear infection... please advise

My 2.5 month old son has been running fevers anywhere between 101.2 and 102.7 since 6pm yesterday (almost 24 hrs). Prior to that he was running low grade temps of 99.5. Throughout he has never stopped wetting diapers, he takes a bottle. He’s extra cranky. I took him to a walk in urgent care this morning when they opened and ran a flu test (neg). They mentioned one ear looked red. Ok, so, started him on antibiotics. My question is, even with Tylenol on board I haven’t been able to get his fever down below 101.8 (rectally). He just feels so hot and he’s getting crankier as day progresses. Should I take him to ER?