Bruises without trauma usually indicates an underlying clotting insufficiency. It can be due to low platelet count (platelets are responsible for clotting blood). Although abiraterone is not known for decreasing blood cell count but this possibility should be ruled out. The other possibility is prostate cancer progression affecting marrow and blood counts. The tiredness can be secondary to disease progression OR mineralocorticoid deficieny or hypokalemia (low potassium levels) associated with abiraterone. Please discuss this with your treating oncologist. An early appointment is suggested.