Hello there,Please be patient, as I may be in the operating room, with a patient, or driving but will get back to you ASAP.
You may have very concentrated urine causing it to be dark and stain your underwear. Also, this may be blood in the urine. The best way to determine what is happening and if anything serious is going on is to just see your doctor and have a urine check. This will tell you if there is anything to be worried about. Hopefully this helps.