Since what you describe sounds so much like the kind of pain women have with ductal yeast infections, I would not agree that there are "no signs of yeast infection".    Also, the timing of the onset of pain is suspicious for yeast.  
This woman and her baby should be examined completely by someone who has seen yeast of the nipple and breast.   If after examination no additonal signs of thrush are identified, there may still be reason to treat mom and baby with at least topical treatment.  After all, "excruciating" pain  reflects some problem.
tracy throckmorton rn ibclc
portland oregon