If I have severe insomnia, sweating, fluctuating temperature and tremor in right hand, does it mean I have fatal insomnia, or could there be a treatable cause?

Wrong diagnosis. Familial Fatal Insomnia is a very rare syndrome, and considered a prion-associated illness. There are no families that I am aware who live in India, and the sporatic form there are less than 10 cases reported. The diagnosis is based on genetic, family history and clinical symptoms, which at least at the outset, you do not fit. See your physician rather than creating a diagnostic "zebra".
Who diagnosed you. First of all insomnia is a very rare diagnosis. So need more information. You need to give a very good history and essentially start again .