Go to the EMERGENCY ROOM ASAP!!!!!!!
See a doctor immediately. Leaving a tampon in there forthis length of time can cause a serious bacterial infection which can lead to toxic shock, as you are complaining of pain it is highly advisable that you seek medical help straight away.
Best Wishes, Dee.
You need to see a doctor, fast! If a tampon is in you for more than 8 hours, sometimes you can get a disease. It's been in there for a week, and you can't find it? Grab a phone, Now.
Go see a doctor immediately. If you are in that much pain you need to go.