Autism Spectrum Disorder or Condition is a lifelong condition that starts at birth.
No event can cause autism (according to present knowledge) although some events can cause
symptoms that may also be included in autism.
One example is stroke. However, in such cases, a person who suffers from symptoms similar to that that someone suffers from autism suffers will not have autism but will suffer such symptoms due suffering from a stroke.
For more advice on the matter you can seek an assessment from a qualified professional ideally a clinical psychologist who specialises in Autism Spectrum Disorder.
Such a person may be contacted at your national Autism advice service.
Hope this helps.