I don’t quite understand what you’re describing. What do you mean by’ ‘the scrotum skin keeps expanding on the penis’? Is the scrotum swelling? Did this just start recently? Did you suffer any type of injury to the scrotum and/or penis? Maybe you SHOULD submit a photo - I really can’t picture what’s happening.
But in any case, I think you’re going to need to see a Dr. or possibly even a Urologist. This sounds very unusual & I’m not sure anyone here could help - altho we do sometimes have Dr’s reading these posts & advising...