I've never heard that adults don't get ear infections. I've complained about it before, and have never had a doc say that to me.
I have chronic sinus infections, and used to have sore throats all the time, but that has lessened in the past couple of years. Lately I've had what I thought was a cold coming on, and it went away in a couple of days. I think mine is just something going around. I'm a travelling art teacher, and I see about 650 kids a week, and usually get everything that's going around. A lot of them will sneeze and cough in your face. I've learned to exhale quickly as soon as I hear it, and move away quickly!
I also live in New England, the capital of sinus problems. It's said that you can't live here for long without developing one.