I guess the white things with the strings don't turn red anymore.
Periods which every young women experience once in a month or after every 26-32 days, can last for 1-7 days. At the end of the periods, blood becomes light in color. This indicates that periods are about to end. After this bleeding seizes and endometrium starts to proliferate for the implantation of fertilized egg. This might be the answer of your question.
You could be pregnant, stressing, or excessive weight gain or loss (change in diet)