I Have Been Having Episodes Of Flushing On My Extremities

I have been having episodes of flushing on my extremities (hands, arms, face, neck, chest, feet). At first only occasionally but now more frequently, For the last two nights they have been really bad and are followed by chills. I thought this may have been caused by niacin but I didn't take it tonight and it still occurred. I also have a slight swelling and itching in these areas when this happens. What could be the cause and what is the best way to deal with it when it happens?