I feel any superficial antibacterial solution for few days may cure it a bit.

This may be caused due to exposure to chemicals on the floor or elsewhere. Could be a local infection. Kindly go for a one on one discussion with a vet so that other factors may be ruled out and it may be treated

It looks like his scrotal skin is inflamed. It can happens due to many reasons. Example- contact allergic reaction, infection of the scrotal skin, and infection in the blood, which shows symptoms like this. It can be treated based on a clear history and a  complete understanding of his whole system. Kindly get a consultation for him to identify the root cause and cure it.