Vagina problems - Bartholin cyst?

A couple of hours ago I had mild discomfort in the viginal area and looked to see that my left vaginal lip was red and hard and swollen. I'd been producing a lot of discharge over the past week but hadn't had any swelling until a couple of hours ago. I took a bath, with bubble bath, to see if it could soothe the pain in case it was just an irritation. However, if anything it had made it worse, as now it is even more swollen and red around the left area of the inside of the left vagina skin. When I touch it, it's extremely hard and almost like a small swollen bubble on my lip. I am extremely worried about this. Should I just leave it and see how it goes, or should I take action? I have looked on the internet and seen various vaginal infections you can get but I don't know if I have one. I am 14 years old, and am extremely nervous and embaressed to mention this situation to my mum as I am quite secretive and I'm really nervous about telling her. How can I tell her? Should I tell her? Or should I leave it for a couple of days and see if it fades down. (Please note, it's only the left lip, the right one is fine).

10 points for best answer! 

Thanks,

Sarah