Sounds like you should get your thyroid function checked.
http://napervillesun.suntimes.com/lifestyles/4780786-423/feeling-too-cold-too-hot-signs-of-thyroid-problem.html
I hope you don't take this the wrong way. You are too young for menopause. I would go to the doctor and have him check for Mononucleosis. It sounds like the symptoms. I know its pretty easily picked up. They call it the kissing disease but that's not necessarily true. When school age kids get it they keep them home from school so as not to infect others. Also for Lyme Disease, though I am not sure of all the symptoms I know fatigue and flu like symptoms are a couple of them. Also, Chronic Fatigue Syndrome. Google all of these and see if any of these fit. Hope this helps.