The same information that a doctor performing triage uses to determine how sick you are can be done at home by you. I often read about this dilemma, go to the ER or call the doctor off hours and I too have debated whether to do one or the other.
You have a chronic condition, CF, that makes sudden pneumonia a reality. I go through entire years having more time with pneumonia than not but each pneumonia is a remarkable change in medical parlance.
I assume you don't typically have blood streaked mucus, so it by definition is remarkable which means it is a primary thing to tell your doctor. Take your vitals, temperature, pulse-ox and blood pressure before calling the doctor or deciding if you should be calling or going to the ER. Take one of your returnable Christmas gifts and exchange it for a pulse-ox or BP cuff. I assume you have a good thermometer? If you've got streaked mucus AND your oxygen is low, for you, and/or a fever and/or a racing heart or heart pound and for us, BP at any age, are all data your doctor needs in order to make a health decision for you.
The ability to measure and understand these vitals will tell you the probability of your needing more than bed rest. Assuming that you have a fever, pulse-ox shows you're hovering around 90% and you've got blood streaked mucus, any trepidation about calling your doctor should be gone and you have solid data to impart when you call.
Any doctor who doesn't understand that his or her chosen profession is 24/7 should find a teaching job. Entire industries have arisen to offload the round the clock business. We CFers have legitimate reason for calling the doctor over going into a germ filled limbo of the ER where the smartest doctor barely knows what CF is. We go to the ER when we have an untreated infection, higher than 101.9° fever that can't be controlled, dehydration due to being sick, lower than tolerable oxygen or uncontrollable pain.
Chest infections are serious and they must be kept in check. It doesn't matter if I have four pneumonias a year or one every four years, chest infections are top priority. All substantial infections are accompanied by a fever. Keep in mind an infection in the chest is killing lung cells which may not grow back, depending on your age. You have this emergency handled and the Holidays are booming business. Medicine like florists work overtime on special occasions. Something about the stress and extra exposure brings them in.
Happy New Year,
LL