vaginismus?

So I was just wondering are there any symptoms for vaginismus as when I try to insert a tampon my vagina tightens and I can't put them in properly as it's so uncomfortable and painful. I'm not sure if it's just me doing it incorrectly but I remembered seeing about how your vagina tighten so things can't get in there. I've told my friends but they just find it funny and won't be mature, I am generally concerned. Any help is grateful thanks x