During the first few days of March, I was experiencing a lot of brown vaginal discharge. It isn't the first time it happens, but usually I experience it for a couple of days before my period goes away. This time it happened before, which I found strange. I was a bit worried since I wasn't expecting my period until March 15th (and this started happening on the 3rd, give or take). Then I got my period on the 6th of March. Normal, for the most part painless (which is also unusual for me). It stopped entirely on the 13th. Then on the 15th (day I was originally expecting my period to come), the brown vaginal discharge started again. I figured it would be light and only last a day or two but I was wrong. I'm still experiencing it and today there was actually red blood. So basically, I have had my period since March 6th, with only one day of break in between.
I am 18 years old and sexually active. Have only ever had one partner, and I'm his first partner as well. We use condoms for protection so I know it can't be an STD. I don't take birth control, or any other type of medication. I've taken "Plan B" twice -- but that was over 10 months ago. I've never been pregnant/had a miscarriage. Nothing. We always use protection. And I haven't had intercourse since late April. For the most part I use pads, but I do use the occasional tampon. I've always had an irregular and painful cycle but it's never done anything this strange. My period usually lasts no more than 10 days and it's heavy the first 3-5 days or so.
I'm really concerned here. What's going on?