Is the blood that came down after a miscarriage and continued for 22 days, then stopped for two days, then returned heavily with clotted pieces, menstrual blood or istihadah (non-menstrual vaginal bleeding), especially with the presence of a fibroid, and after performing ghusl (ritual purification) and fasting, light and intermittent spots of blood appeared?

This blood you saw during the miscarriage is considered blood of istihadah (definition) (irregular vaginal bleeding), except for any portion that coincides with the time of your regular menstrual period. You must pray and fast throughout that entire period, except during the time that matches your usual menstrual period. If you omitted prayers at a time when you thought it was menstrual blood, then make up what you missed. You must also make up any days of Ramadan (definition) that you did not fast. If the bleeding continues after that, then you are a mustahadah (experiencing irregular bleeding), and you must follow the rulings for a mustahadah by referring to your previous habit or by distinguishing (between types of blood). Otherwise, you should sit out for the predominant duration of menstruation, which is six or seven days, then perform ghusl (definition) (ritual bath) and pray. You must take precautions and perform wudu (ablution) for every prayer after its time has begun.