Hello, I m 18 years old. I first got my period when I was 13, and since then my periods have been fairly regular, always falling between 3 and a half weeks to 4 and a half weeks. My last three periods have been only 2 weeks apart. I haven t noticed any significant change in the heaviness or length of the periods. I ve always had a small amount of white/yellowish discharge but in the days leading up to this last period it became brownish. I am sexually active although i haven t had sex within the last few months. The only thing i can think of is that i started using tampons instead of towels exactly before my periods became irregular. Could this have anything to do with it? What else causes this?