What Could Be The Cause For Freezing Sensation In Head During Hot Season?

Hi Doctor My name is Cris and I live in Australia for couple of years. In the last 2-3 years I have noticed a bizar fenomen that have been happening to my head: everytime when the temperature gets down for example under 20 C degrees my head suddenly get very cold and I need to put something on him to protect it against the freeze sensation. In winter which in Australia we couldn t say that is too cold, I really have to face troubles. At the temperetures over 25 C degrees the situation becomes opossite,my head getting very warm with an abundent perspiration around the head and my neck. I thought it is a neurological issue and last year when I was in my country I overpast a RMN test. With the results of that test included a Cd s I visited three neurological doctors. All of them told me the same thing that there isn t any problem of neurological point of view. They didn t recommend me any treatment and I came back to Australia with the same problem. In the last year I have also noticed that my hair has been getting lost more and more even if I had a rich and healty one. Also I ve observed problemes (pain for example) with my eyes. I am really afraid this time and I think there is something bad with the blood circulation in that area of my body. I m saying this as I learnt in my school that our blood works as a thermoregulator into our body. My hair doesn t dropp down but it dissapears everyday. It is like he melts. And continuos troubles with my head temperature. I am almost dispereted because I don t know what it happens to me and how could I help myself to cope this situation. I would be very grateful to you for a professional and useful answer. Thank you very much and apologise for my poor English. PS. I would follow any test ,treatments or any indication from you. Regards Cris