Oh, I forgot to say - I also have other friends' anecdotes that it say it may be nothing.
There is one hell of a cold going around this year, it was in Australia last August/September and it caught up with me in London in December. Two close Australian friends got it badly enough that they both ended up with chest xrays and finally being diagnosed with asthma for the first time in their lives, both over 50. They both recovered, so the diagnosis was sound. A mother of a friend of mine in the UK has had a similar experience - chest x-ray and asthma diagnosis, though she is not doing as well, but she's a lung cancer survivor, so it's more complicated. I got it my self a few weeks ago, and the nagging cough stuck around for weeks (no where near as bad as the OP, but coughing to the edge of vomiting, so not great) and was relieved with Ventolin.
So it's probably just a nasty chest infection, but follow it up to be sure - which you are doing.
And when you get to Vegas, hire a convertible Mustang and drive to Death Valley