What is wrong with me?

I have been nauseous just about every day for about 3 weeks. It usually goes away once I eat then within about half an hour to an hour I'm sick again. Today a plethora of other things hit me that are out of the ordinary for me. First off, I took a 5 hour "nap" after getting 8 hours of sleep last night. I had absolutely no energy which is atypical for me. I was also really hot, not from physical exertion, just sitting there and all of a sudden I was burning up. I'm usually the one that is ALWAYS cold. I also got really lightheaded and dizzy after walking from one room to the next. I also noticed that my are incredibly sore. I'm not sure if I'm pregnant or if something else is seriously wrong with me. My periods have been really messed up lately. I had one last month but then spotted for about 2 weeks so I'm not really sure when I'm supposed to start again. I'm just so confused by all of this. Any help would be greatly appreciated.