I've had a dull, burning pain in my lower left side for the past 3 months. Lately, this pain has also radiated to my lower back and groin and sometimes I feel it in my left leg as well. I was told that it isn't a urinary tract infection, but I have no idea what it could be caused by. My periods are regular, though the pain is intensified during the first few days of menstruation. I haven't noticed any discomfort during urinating, so I'm not sure if it's a kidney stone. I'm 19 years old.