I suppose anything is possible, but personally I cannot believe a Covid injection (neither a live virus nor related to pneumoniae) could cause pneumonia.
I have no doubt that some of the reports we hear ARE vaccine reactions - but every vaccine reaction I have ever had - and there have been several - was more immediate.
If you work in a hospital, you likely came upon some strange new bug there - my daughter caught several from her nursing work, including TB when she worked in the county jail, and Covid in March 2020 working in the ER.
You could ask your doctor to report it to VAERS as a possibility.
Sue