Greetings! spontaneous bruising is associated with n number things! few examples are Blood disorders, including problems with blood clotting such as hemophilia A or hemophilia B 1.Blood-related diseases such as leukemia 2.Liver disease, such as cirrhosis 3.Lymphomas 4.Certain disorders in which bone marrow cells grow at an abnormal rate 5.Nutritional deficiencies, such as deficiency in vitamins C, K, B12, or folic acid 6.Sepsis, or severe infection in the bloodstream 7.Systemic lupus erythematosus (SLE) 8.Allergy-related disorders But the most frequent and ignored cause is due to Nutritional deficiency! as mentioned above Vitamin C and Vitamin K and B12 plays important role , another common cause of bruising might be allergies! So i would suggest a healthy diet with lot of vitamin rich food and find out if your allergic to anything!