Hi,
Shortness of breath could be due to various causes and each will have its own typical manifestations.
As you are concerned about pneumonia, let me briefly explain you that in case of pneumonia, there should be fever, productive cough, shortness of breath, chest pain may or may not be there.
You don't have these symptoms it's less likely that you might be having pneumonia.
Next Steps
if it persists you may get yourself clinically examine by physician.
a chest x-ray and CBC might be helpful in excluding pneumonia.
Health Tips
for any further query you may consult online.