Grrrrr.
I hate when doctors act like that and give the rest of us a bad name. Trouble breathing is a same day visit always. I am sorry you got the big brush off. Earlier, someone said be persistent. It is unfortunate but true that the squeaky wheel gets the oil.
As for the OTC medicines, the more they are rigorously studied, the more it shows they do very little or nothing for respiratory infections. The only exceptions are old antihistamines and decongestants have a little effect.

Good luck getting well. See a doctor!