What Causes Hot Flashes From The Base Of The Chest Towards The Face?

Hello, I am in need of advice, I have had a Hysterectomy about 4-5 years ago everything was taken out including ovaries, I went into immediate menopause with severe Hot Flashes back then , The dr gave me premerine at that time, I took for about 4months or so and stopped. I was fine after that just an occasional hot flash here and there, but nothing like it was before... Now I am suffering with severe and I mean severe Hot Flashes going from my base chest breast area then straight up thru my whole face and head and will break out into a sweat then after 3mins or so it will go away, then in about every 15 to 20 mins after that episode it comes back.. is this normal? I am really getting frustrated because I am so uncomfortable every single day and all day long, my face turns red and flushed looking then clammy and I keep my house on the coo / cold side always on every season, I as well have this happening during sleep too and find myself throwing off all covers and at times all my clothes ( night gowns and such ) then when it goes away I am cold so the blankets are back on but I find this happening mostly during my waking hours than at sleep time. PLEASE HELP!!!! I can not take this no more, so any advice will be appreciated. .... Thank you.. - Bonnie Stansbury