No periods,,and confused?

Someone i know hasnt had a period in 3 months...She has taken 3 pregnancy test and they are all negitive..She is confused and ask me for help i have no clue what would make this happen..She is on ortho tricyclin for birth control..But i dont think that should do it. I just dont know what to tell her...any help at all would be wonderfull.thanksNo periods,,and confused?
Sometimes pregnancy tests aren`t acurate. She should make a doctor`s appointment immediately - if she is pregnant, taking the birth control can harm the baby. The doctor will let her know what to do and where to go.
Obviously, she should see a doctor instead of asking you who I assume is not a doctor.