2,112. Finding a Stain on Shabbos or Sunday
Hilchos Issurei Biah 9:17
Let’s say that the woman in our previous halacha didn’t see blood on Shabbos but she did find a stain during the first hour of Shabbos. If she checked herself on Friday and found herself clean, she only counts from the second stain, which was found on Shabbos. This is because both stains were found within 24 hours of one another. If she didn’t check herself and didn’t know if she was clean in between stains, then she starts counting from Friday. Therefore, if the woman sees blood on Sunday, she must be concerned that she might be a zavah.
Hilchos Issurei Biah 9:18
If the woman found the second stain in the second hour of Shabbos, she is considered unclean for two days because the stains weren’t found within 24 hours of one another. This is true regardless of whether or not she checked herself. If she sees blood on Sunday after 24 hours, she must be concerned that she might be a zavah. Let’s say that the woman found a third stain in the first hour of Sunday. If she checked herself and found that she was clean, the stains are not considered consecutive and she need not be concerned about being a zavah; if she didn’t check herself, then she must be so concerned.