Wow, this sounds like when I was diagnosed! Again, in my experience, this severe an infection is only going to get worse.
I understand the ER reluctance to give you an antibiotic when you need the exact infection diagnosed, but it sounds like this cannot wait - your primary might need give you something to knock this down while you wait for an appointment. Relieve pain and any coughing with OTC meds - run by doc first.
As for staying comfortable - do you have an inhaler to help with shortness of breath? If not, call your primary and ask for one. And possibly a nebulizer.
Again, also talk to doc about getting a sputum sample to speed up learning what is making you so sick.
Some of us (including me) have found some comfort in a product called "Breathe Easy Tea" by Traditional Medicinals - widely available in many supermarkets, health food stores, on-line and even larger WalMarts.
In the meantime, get copies of the CTs and any tests so far to expedite getting treated when you can get an appointment, and don't discount trying to get at least a phone appointment with Mayo (https://www.mayoclinic.org/appointment-request) or National Jewish Health in Denver (https://www.nationaljewish.org/doctors-departments)
Can you share what area you are in? Maybe another member can offer a suggestion for a doc.
Please stay in touch with me and let me know what kind of help you can find.
Sue