Tubal infection and pregnancy. There are probably more. You may want to check on it growing into your lining or piercing its way through and into your inner abdominal wall.
I really do not trust those things.
Although, waiting only 2 weeks past due date to have it taken out is probably okay.
Its possible those symptoms are caused by hormonal withdraw.
I'm not a doctor so cannot really tell you whether its safe or not to leave it in.
I can tell you that if it were me, I would get it out ASAP and that I would probably wait the 2 weeks to let the doctor do it. :-)