1. With regard to the yellowish or brownish discharge before the menses, if it comes at the usual time of the period or a little before, then it is part of the menses and you should refrain from praying and fasting at that time. 2. The yellowish and brownish discharge that appear after the bleeding and before purity (i.e., before you become pure from menses) is part of the menses. 3. The yellowish or brownish discharge that may appear after the purity does not count for anything.

The spotting that appears after becoming pure from menses is not regarded as menses, because it is not ongoing bleeding. So, you have to fast and pray, and do wudu for each prayer.

Muslims scholars agreed that it is prohibited for a menstruating woman to pray, whether that is obligatory prayers or supererogatory. Based on this, if a woman does that she has to repent to Allah and to seek His forgiveness for what she did.