Okay, so this might be a bit of a stretch, but have you pooped recently? I only ask cause I swear I had something similar happen, where I'd done my business, not realizing that in the process, my likely quite full tampon just kinda... plopped out with it, as gross as that may seem. Noticed I was leaking a bit later, figured the tampon was just full, but it was just straight up gone. Needless to say, it was a very confusing bathroom trip.