Thank you for reaching out to us.
If you saw that you had a cut in the vaginal area that was bleeding and you are confident that it accounts for your
stain, then the stain on your underwear does not affect your
clean days.
The
bedikah you describe also does not affect the validity of your clean days, because the central part of the cloth was clean and you can clearly distinguish the blood on the edge as coming from a cut. In this case, you should omit today's afternoon
bedikah.
If something like this happens again, it could be helpful to use a mirror to guide your
bedikah, so you don't further irritate the cut.
If you find any bleeding
after relations, you can also attribute that to the cut if it is consistent with what you've been seeing there.
Please let us know if we can be of further assistance.