Talk to General Physician on Sweating, Dizziness, Underweight

Hello Honorable Doctor’s, :- I sweat too much, even in winter’s. :- Not gaining weight at all ( i eat very well). :- Too much scalp hair-fall as well as chest hair fall (No hair fall on Beard). And my nails are growing very fast. :- I often feel dizziness, BP goes down and i fall down. I think these symptoms are enough to understand my problem. Please guide me regarding this.