It could be nothing. But I would get it checked out, if you're not that close with her, you could just tell her that you're itching, could be a yeast infection for all she knows.
I am really close to my mom so I can tell her anything.
But I realize some girls aren't like that with their moms. I am sure that if you told her, you might be in a little trouble, but she's more concerned about your health and well-being more than anything. The way I got close with my mom was talking about sex, and other stuff like that. She didn't freak out quite like I thougt she would. You never know, but you do need to get that checked out. If it's clamydia and you go too long without treating it, it could cause some irreversible damage wich causes you to be infertile, and you really don't want that. Talk to her, she'll understand.
Good luck sweety.
<3