Based on what you said, it was okay Friday, but then you were out in the allergens. There is a LOT of microparticles going on outside.
I would bet being out there was a bit early....too soon after getting the shot. If you do go out, I would (Corona PTSD) "wear a mask" and see if it filters the air. Otherwise, I'd probably stay in and away from the irritants for a day and see what happens.
It would be similar to a not-so-great air quality day in the summer. People with respiratory issues are usually cautioned to stay inside. Given that you are just coming out of walking pneumonia, you have to still be careful this early.