Sudden black bruising with pain in the back and waist, considering lumbar injury, capillary hemorrhage, and so on. 1. Lumbar injury: the back of the waist suddenly black with pain, consider lumbar injury caused by, such as lumbar transverse protrusion fracture, lumbar muscle strain, ligament injury, accompanied by obvious pain and lumbar spine activity is limited. You can take bed rest, local ice, external Yunnan Baiyao aerosol. 72 hours application of safflower oil or panax ginseng injury tablets. 2. Capillary hemorrhage: if there is a coagulation dysfunction, such as blood disease or allergic purpura can appear suddenly back waist suddenly black and pain, through the blood test and coagulation function can be clearly diagnosed. Therefore, if you have sudden black bruises and pain in the back and waist, you should reduce your activities, and it is better to go to the hospital for examination to clarify the cause of the disease and further treatment under the guidance of the doctor. The above drugs should be used under the guidance of a doctor, avoid self-medication.