Hi,
I’ll suggest consulting a urologist and getting your son examined. He might need further tests also like an ultrasound of the scrotum to rule out the possibility of a hematoma (clot formation) within the scrotum. The possibility of any damage to the testicle also needs to be looked into and can be ruled out with the help of the ultrasound. I sincerely hope that helps. Take care.
*And now he has no feeling in it*