What Causes Severe Heat And Sweating?

I am a 45 year old woman & I had my right thyroid gland removed 2 years ago. Since then I have gained 28lbs eating virtually nothing, I'm always on a diet. My doctor doesn't seem concerned about my t3 & t4 levels and has never tested them. I have become very tired & sleep sometimes for 14 hours of the day & more, my periods are virtually non existant since then (I've had 3 in two years), and I suffer from severe heat & sweating. My doctor thinks it's the onset of menopause which I accepted but I would like a second opinion. Thank you.