Do I have bronchitis, or is this something else?

it sounds like bronchitis to me, and yes being around that fireplace and/or the smoking uncle could have caused an irritation in your throat which made it susceptible to infection, after your throat was infected the infection moved lower and lower into your bronchi. as long as your dr has given you some kind of antibiotic and you are resting and drinking a bunch of fluids you should be fine.