From: Rabbi Moshe Sofer
To: Rabbi Ber
On the first question, the Chasam Sofer rules that a woman who corrects a miscalculation of her tevilah date is believed, since counting errors are common and retraction is valid under both the neder and hodaas baal din theories of shavya nafsha; however, if the correction comes on the very night of the originally stated tevilah, a scrupulous person should be stringent. On the second question, he rules that vaginal blood cannot be attributed to hemorrhoids when the hemorrhoidal channel is functioning normally, though he permits leniency regarding kesamim and advises practical procedural guidance for bedikos during active hemorrhoidal bleeding.
Source: Shu"t Chasam Sofer YD §185