Turns out, he had not just a double ear infection but also RSV, a respiratory virus.
He has a cough and a seriously runny nose, and he is wheezing a bit. But besides the physical symptoms, you would never know he is sick. He is playing and laughing just like always.
He got an antiobiotic for the ears, and we are doing breathing treatments with a nebulizer for the RSV 3 times/day for a week. Let's just say getting a baby to sit still for almost 10 minutes with a mask over his face is not the easiest job in the world.
But after a lot of struggling, he finally acquiesced.