I just returned from the doctors office for this same problem. I did not know the tampon was in there. Not even sure how long it was in there!
I was having cramping, sweats, discharge with a brown tinge, and a horrible odor. The nurse practitioner prescribed doxycycline for infection. This is the second time that this has happened. The last time was two years ago. I keep track of my usage of tampons and do not know how this can happen again!
Makes you want to give up the tampons! They usually fall out, not up!