There can be many causes of bleeding from urethra. It can be due to Urinary tract infection
, urethral trauma, meatitis or inflammation of the urethral meatus, urethra foreign body, stones in urinary tract, urethral calculus and benign and malignant growths in the urinary tract. There are some onvetsigations required like Urinalysis, Urine culture, X-rays of the kidneys, Cystoscopy, IVP, Abdominal ultrasound and CT scan of the abdomen.
My sincere advice is to consult a urologist.