sequence

Keeping qadha fasts in sequence

Q: Suppose a person has missed fasts of so many years. She also has to fast the days of her periods of the previous Ramadan. Can she first fast for the period days and then make up the fasts of previous 5 to 6 years? Or the fasts have to be kept in sequence. By keeping in sequence it might happen that she doesnot get the time for keeping her period fasts before the next Ramadan.