Cycle while on Provera

I'm taking provera from days 1-21 and then off for the final week in the month. February is the first month I have taken it on this schedule. Previously, I had taken it daily throughout entire month. Well, I got what seemed like a regular period about 6 days after stopping the provera on day 21. It lasted 6 days. Then lo and behold a week passes and I get the period again, this time very heavy and currently on day 6 of bleeding. So this past month I started two periods exactly two weeks and 2 days apart..I'm on provera for hyperplasia without atypia. No malignancy,but a year of very heavy bleeding and clotting. Am 49 years old. Anyone know what's going on? To tell you the truth I'm scared of the provera and side effects but I've had to take it because the bleeding was incapacitating me.