Hi , I have a 16 year old daughter who has been on her period for 2 1/2 weeks . She was taking birth control shots but has been off for 4 months. Why is this . Is it because she has low calcium

There are dozens of reasons for having a extended period. There is no way to determine why without proper medical tests. She will need to be taken to her doctor for an exam

Coming off the depo provera shot can cause prolonged bleeding months after the last injection.