As a background: Near future (next 1-2 years) and civilization has come to a crashing halt and fallen apart around our ears. There's literally no way to re-supply unless taking a very, very risky trip into a city and that city is a few days by horseback away. Technology, if you have power, will indeed work. The locale is very, very rural -- deep into farm country with a significant forest & river nearby.
Considering this is set during spring melt said river is also flooded heavily leaving them cut off from any help that could have come anyway.
What they have access to: One Canadian university trained surgeon/medical doctor with at least ten to fifteen years of experience, an ambulance's worth of supplies and a warm and safe location to treat the unfortunate person who has fallen ill.
The person fallen sick is a normally healthy, but older, man of around 65.
Smoking (but he hasn't been able to because cigarette supplies ran out months before so he had to quite 'cold turkey) and was an active smoker since around his thirties and somehow has avoided lung cancer.
Coffee... for those familiar with NCIS think Gibbs level of coffee drinking. Cannot, and will not, go without coffee. Unfortunately, coffee supplies ran out a while before he got ill as well.
Other than that he's healthy and leads an active lifestyle... for a salesman from the city. He's not a tough farmer or cowboy type and is built rather compactly and slim.
I'd ideally like him to get really, really sick but not sure just how far -- given the circumstances -- is safe to take it without killing the character off and just how the doctor that they have access to would be able to treat it, and what she could do to treat him.
I searched online using Google for:
Causes of pneumonia
WebMD and wikipedia had some okay explanations that for a layperson were easy to follow but fuzzy on exact details. Everything else (ie: Mayo Clinic, etc) went right over my head even with a dictionary beside me.
I'm looking for steps in treatment, how he would feel, how long he'd be down and what she could do to help him recover... and how 'recovered' he would really get.