I Have Not Been Feeling Well For About 2 Days

i have not been feeling well for about 2 days now. it all started when i woke up my throaght and my head and a stiff neck were hurting. and i had no idea why? and last night I COULD NOT go to sleep and it was also weird because when i was asleep last night it all of a sudden i got REALLY cold and then about an hour later REALLY hot i don't know why?