Chills with no fever

I do have Rheumatiod Arthritis and at first I thought my symptoms were me flaring up.  It began with muscle and joint pain and severe chills.  I constantly checked my temp and it never went above 99.6  My temp has been normal for the last 24 hours(for me), but the chills still continue sometimes causing my teeth to chatter and I have been walking around with a coat on because I am so cold.  Then a few hours later I am so hot I am sweating and take it off only to cause the chills to come back.   I am also extremely fatigued.  I have had RA for 10 years and this has never happened before (chills with no fever).  Could this be something else going on?  It is so hard to tell because my RA symptoms are so much like other diseases.