I fainted and woke up in ambulance. i was admitted to hospital. they thought i had a stroke. mri showed mild chronic microvascular disease. i'm 48.

Explanations?: From your description, does NOT seem like you had a stroke, but your docs need to confirm causation. Did you really faint or instead have a cardiac arrhythmia, such as Stokes-Adams attack, or a seizure? A transient ischemic attack in the vertebral-basilar circulation can cause "drop attacks". Get a second opinion if necessary but aim to prevent future spells.