I have had a couple of issues following urology treatment. On one occasion my urethra inside the penis was punctured, this resulted in the whole penis swelling up as urine got into the soft tissue of the penis,it was also very painful.
On two other occasions the foreskin was not pulled back over the head of the penis. The foreskin swelled up like a balloon. The remedy for that was applying an ice pack or a bag of frozen peas to the penis. Once the swelling went down lubrication was applied to the head and foreskin and pulled back over the head.
In your position I would be ringing the ward that discharged him and asking for advice.
Thanks Chris