All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
If a woman does not have menses until after sunset even by one moment then her fasting is valid and she does not have to make up this day even if she feels that she has menses before this time. Feeling that you have menses without really having menses does not affect your fasting, unless you really have some blood discharges.