merrychristmas, interesting. I wonder if the body, as a result of hormone and neurosteroid deprivation due to finasteride use, attempts to counter or absent proper hormones speeds up metabolism for cyclical periods until it wears itself out, leaving the body in a mostly hypothyroid state.
thyroid.about.com/cs/basics_starthere/a/symptoms.htm
My guess is this is another one of the more difficult to pin down patterns of body response with finasteride use as the subset who experience this alternate between hyper and hypo leading to conflicting symptoms. Most likely the hyper symptoms are most pronounced in the beginning and the hyper states come less and less frequent as time goes on eventually leaving the body in a mostly hypo state.
However this is just a guess as we cannot exclude the effect of other hormone deprivation leading to similar symptoms.