girls/docters only vaginal/period heath

Could it have been a tampon?

What is the cylinder thing that fell down? Could you make it more specific.

Forgotten tampon? These have been known to cause illness. If you left it in since last monthly time, you need to be more careful in future. Surprising you did not know what it was. Can you talk to a female relative such as mother or aunt, or school nurse? Unless of course you are a troll.

Any possibility it was a blood clot? Whatever it was, you need to have it checked out. Was there any cramping or heavy bleeding afterwards? You can PM me if you want to discuss this offline. I will urge you to be attentive to puzzling conditions. If there is a problem brewing it is best to get treated early. Waiting only gives a problem more time to get complicated. Good luck.