What Causes Fever, Sweating, Freezing And Spotting?

I am 35 year old female. I have been running low grade fever for several days. I sweat one minute and freezing the next. I have had the depo shot twice now with my most recent at the end of August. I did start spotting about 4 days ago and now bleeding pretty regular. I also started celexa about a week ago. Could either of these be causing this or could i just have a virus? Really tired abnd fever