What is the ruling regarding a girl who did not fast most days of Ramadan due to menstruation, then another Ramadan came upon her, and she is afflicted with osteoporosis and her menstruation has not stopped until now? Is anything incumbent upon her?

The first Ramadan (definition) you missed due to illness must be made up before the next Ramadan. If you do not make it up, you are obligated to pay an expiation of feeding a poor person for each day, unless there is a valid excuse for not making it up. If blood exceeds its legal limits, it becomes istihadha (non-menstrual vaginal bleeding). A woman experiencing istihadha abstains from prayer, fasting, and the prohibitions of menstruation for fifteen days, after which she is considered ritually pure. If, after fifteen days, there is a distinct change in the color or smell of the blood, it is considered a new menstrual period. This ruling applies to a woman experiencing menstruation for the first time. As for a woman with a regular cycle, she observes her usual period; if the bleeding does not stop, she is considered ritually pure until she can distinguish the blood or the bleeding ceases for fifteen days. Accordingly, prayers missed during the time of istihadha must be made up, and fasting must be made up in full (for both the period of menstruation and istihadha).