1. Dark yellow stains, with no trace of red, do not usually render a woman niddah, regardless of their size.

Additionally, stains on clothing are not added together when evaluating size. The size of each stain on clothing is evaluated independently. That is to say, a woman can have numerous stains, even of a bright red, each of which is smaller than a gris (about the size of a dime). Even if, added together, the area of the stains would far exceed that of a dime, she is not niddah. Thus, the staining on Sunday did not invalidate your hefsek taharah.

When in doubt about color and size, we strongly advise that you have the stains evaluated by a halachic authority rather than assume that your hefsek taharah has been invalidated. You should continue with your count and bedikot until you receive a definite answer.

2. We understand from your question that you did not do any bedikah on Sunday, and only used a tampon. Tampons are not generally used for bedikot because they cannot reach all of the cracks and crevices of the vaginal canal. However, our site's current Rabbinic Supervisor, Rav Kenneth Auman rules that after the fact or in a pressing situation, there is room for leniency for a bedikah during the seven clean days. In this case, mikveh would remain scheduled for Saturday night if the rest of your clean day count goes smoothly.

This response was updated on 5 November, 2025.