Ok...My girls temps do go up and down..usually the week before they deliver.  I would be taking her temp 3 times a day, same time everyday and writing it down.  When mine go in the 98 degree zone they go anywhere from 12 - 24 hours.
 
I would just keep her comfortable and once that temp drops do not leave her alone. 
Do you have a vet reachable 24/7 just in case?  Do you have a mentor nearby or by phone who can walk you through when labor begins? 
Make sure she is eating well...you want her to keep her strength.  There is a good recipe for whelping pudding (just do a search) and mine love boiled chicken breast if they are being picky about eating their food.  I always feed puppy food when they are expecting too. 
If you have any questions, just post them and we will help you 
