Ok, I'm freaking out here. I'm 17.

Both me and my boyfriend were virgins and have been having sex for roughly a year and four months. Neither had any problems in the lower regions. Recently I went away for about a month and haven't had sex with any other. I went back down to visit and we had sex a few times a day over a period of two days. The third day, it started stinging when I urinated the day I got my period. I thought I was just having a reaction from the added bacteria and period at the same time, thought it was merely a urine infection.

I finished my period about a week ago. One night recently, I had severe what felt like period pain and lower back pain. I still have lower abdominal pain on my left side which gets worse of a night and can barely feel it during the day. Tonight I have started bleeding lightly, only when I urinate. I am wondering if it's an STI or still just a urine infection? Am going to see the doctor as soon as I can. I thought it would go away, if it was only a urine infection. I keep myself clean. The stinging and pains are worse at the moment, and the bleeding begun. What could it be?