Weird discharge.. Females please help?

For starters, I am not ually active and I am very hygienic. I even wear cotton underwear to stay clean. For the past week I ahve been having lower back craps as if I were about 2 start my period. However, nothing has ever happened. The other day I went 2 the bathroom, and on the toilet paper there was a clear discharge that was blood tinged. I have not had any itching or burning or any type of irritation. Another thing that I have noticed is that I have been having a light brown discharge in my panties. It is NOT old blood from a previous menstrual cycle. I dont know what is going on. I think that i have a UTI or a bladder infection, or even a kidney infection. However, I have not had any burning or itching or any type of odor. The bad cramps and aches in my sides are killing me. BTW, it is not ovulation bc I would def. know. Any help would be appreciated