For 4 months ago i started to see that my left pupil has go smaller than the other is it not a symptom of sporadic fatal insomnia?

Yes and No.: I am not sure, but i suspect that it is very rare. Pupillary defects are much more likely to be indicative o other disease and shold be investigated by your doc and/or eye doc.

Fatal insomnia: Fatal insomnia is very rare. Symptoms starts with insomnia in middle age. Fever, headache, attention and vigilance, memory, get impaired. Hypertension, increased breathing and heart rates, sweating, and slightly increased body temperature are also other sign or symptoms of this rare disease. The above symptoms and the majority of them might be caused by anxiety too. Please see your doctor.