If you are not on any medications like anticoagulants, blood thinners or birth control pills (in females) then bruising could be due to clotting disorders, low platelet count, fragile spider veins
, deep vein
thrombus, deficiency of Vitamin B12, folic acid, or Vit K, a liver disease or certain cancers. It could also be due to pressure urticaria. If you are on medications then you need to discuss that with your doctor. Take care!