Dear Mr vinnet
there are some chances of failure of contraception
of this type. But not always.
Mild sideeffects like this are common. But if it makes her feel giddy, difficult to sit or walk or bleed more, it can be a an emergency.
can best be confirmed within one week fo missing period by an ultrasound
such pregnancies if need to be avoided at that stage, they can be aborted by specialist using a syringe procedure called menstrual regulation.