In light of your concerns, you may use white pantiliners during the
clean days. If you could purchase cloth, reusable ones, that would be preferred. A tampon should not be used, since even a drop of blood on a tampon could invalidate the clean days, and also due to the concerns of irritation that you note.
A
moch dachuk is placed so that a woman can clearly establish that her bleeding has ceased. A side concern that bleeding might resume does not override its main purpose. So using a tampon for a
moch would be considered carrying on Shabbat according to many authorities, even if you are also using the tampon for protection because of the possibility of renewed bleeding.
Please write back with any further questions.
