Hi Doc, Welcome to the forum.
It sounds like a virus to me. JMO. Maybe not the medication at all. I had the flu in late Oct. and it was like that. Some school kids are getting colds that turn into pneumonia, so take care of yourself.
Their cold worsens, and they don't even know they have gone into pneumonia it happens so fast. Rest, drink fluids..you know the drill.
Take care and feel better.