My oldest is almost 5 and never had an ear infection, ever. so imagine my surprise when my youngest was about 10 months old and he had a minor ear infection in his left ear! I didn't even know hwat to do since we'd never dealt with it before. he had no symptoms whatsoever, no cold, fever, irritability, nothing. He was at his routine well baby visit and the doctor looked in his ears and seen a little fluid buildup in his left ear.
You are correct in breastfed babies get fewer ear infections. Both my boys are breastfed and we've only had that one time, and it was pretty minor, and we wiated it out and it went away on its own. I don't like antibiotics so we held off for a week to see if it progressed or if it went away. And it did.
It could also be from teething. I know that minor issues can spring up from teething, like runny nose, slight fever, red cheeks, goopy eyes. I know doctors say thats just coincidence but i could tell you to the day when my boys would cut new teeth, red cheeks, then runny nose, 2 days later a new tooth. :)
I hope your little guy is feeling better soon!