Blood spots that appear prior to Menstruation
If yellowish or brownish secretions and red blood spots appear regularly before and after your period then they are considered part of your period so long as the total number of days does not exceed 15 days. Consequently, you cannot pray nor fast during this time.
Yet if your period actually stops and the secretions appear after 1 or more days after your period has ended then these secretions are not considered part of the menstruation. In which case you can fast and pray, as you are considered in a state of istihaadah not menstruation, but you will need to perform ablution for each prayer, after the athaan (prayer call) or corresponding time has come.