Should a piece of cotton be inserted to ensure the cessation of blood, and if a yellowish-red color appears thereafter, should one continue to not purify oneself?

You must perform ghusl (definition) (ritual purification) if the cotton is clean after insertion, as this is jufuf (dryness), one of the two signs of purity. However, if you find a yellowish discharge upon examination, do not perform ghusl until it ceases. After it ceases, perform ghusl and do not pay attention to any yellowish or brownish discharge you see thereafter, as it is not considered menstruation.