Blood in the tip of penis may be due to:
1. Trauma to the uro-genital tract
2. Urinary tract
Investigations like urine examination and if needed an ultrasound
scan of the testicular area will be helpful in clinching the diagnosis.
So...it will be better to consult an Urologist
to find out the exact cause.
So that necessary management steps could be taken.
Wishing your son a Good Health. Let me know if I need to clarify further.
Thanks & take care.