Help!! 😩

I need help... I'm having problems.. Down there & im young so it looks very bad, I can't tell my mom anything, but I need help of what it might be. It burns a little to pee & it sorta is itchy. I had it a month ago but it stopped in a couple of days, now it's back again, right before I start my period, same as last month. I haven't had sex with someone for a month now & I believe the guy last time might've had something, but he swears up & down he doesn't. So now I don't know what to do, I'm uncomfortable & scared of what it might be. Can anyone help?