I'm 18 and have not had my period in 3 months. I'm not pregnant(not even possible). I have had spotting and it lasted about 1-2 days and i have had pain in my lower back and sides. I have no idea what is wrong and its freaking me out. Any ideas?
StephanieMarie, it is not normal for an 18 yo woman to go without menstruation for 3 months. You should see your doctor. It is not necessarily bad but it should be treated.
Many things can cause it, low body fat, super fitness, poor health, medicines, ovarian cysts (known as PCOS with other symptoms, especially if you are overweight as well and have extra body or facial hair or an enlarged clitoris). Only your doctor can say for sure however.