I had the exact same thing about a month ago. In my case I know I have sinus issues. But this was a wicked sore throat.
May have lasted more than 2 weeks. Worse in morning usually; then sore all day. Was getting hoarse, etc. Of course I went to throat cancer too!!! Well, after talking to my sweet brother in law, who offered to take me to ENT, it went away.
The power of the mind indeed.
You know you were treated for infection, but that dang post nasal drip can last for ages. I found using nose spray my doctor recommended helped. But think it just went away on its own.
Now you know it happens. Do revisit doctor if it doesn't clear up. Can't chalk everything up to nerves.