No, diesel engines don't have ignition coil as they work on compression ignition and not on spark ignition as in diesel engines. Glow plugs used in diesel are like small electric heaters which use the mechanism of heating due to resistance during electrification.
Clarithromycin is another antibiotic treatment for walking pneumonia. It is more powerful than even erythromycin as it is also used to help treat HIV/AIDS patients. It works by interfering with the protein synthesis of bacteria, which prevents them from growing further. It is given in the form of tablets or a gel.
I believe pneumonia generally shows up on x-rays, so I'd wait until Monday & see what the docs have to say. Staying away from alcohol, resting, eating properly & lots of fluids is still a good idea to help you recover. Viruses can last a long time & there aren't many effective treatments for them.