If the odor is intermittent then the anal glands might be at fault if she is full of pups stool might be pressing against those glands.
www.marvistavet.com/html/body_anal_sacs.html
You take a dog's temp rectally being careful to lubricate the thermometer and not to push in too far so as not to hurt the rectum.
If the odor is almost fishy smelling it could be anal glands.
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