You're worried, go and have it checked. The GP or a walk-in clinic should be both be able to do this.
What makes you think it's possible? If you can feel your cervix, the thing that feels 'like a nose' at the inner end of your vagina, you'd be able to go, 'no tampon there', because you'd feel it if there were. You can also get a plastic speculum so you can have a look inside with a mirror.