If blood continues to flow and a woman is still waiting to purify herself, and it exceeds 15 days, then she should fall back to her normal period as a reference. So, she must make ghusl, start praying, and make up the prayers for the days which she did not pray since the time when her normal period would have ended.

If yellowish or brownish secretions and red blood spots appear regularly before and after your period, then they are 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.