The episode of confusion, lack of comprehension, could have been related to your
pneumonia; in some people, something like a
pneumonia can really cause confusion, and this could have exacerbated your myoclonus as well. This is called medically a metabolic encephalopathy. I am not sure from your above report if the small vessel stroke on your MRI was acute (new) or old, but a small stroke can sometimes cause significant symptoms depending on its exact location.