It looks like Staph aureus infection, quite common on the damper areas of the goat - udder, teats and groin.
You will need antibiotic, plus I used a steroid cream (on vet prescription) when one of my goatlings was affected badly. It does go, but may come back....
As they are so young I would load them in the car/dog crate and present to the vet. The steroid cream reduces the itching.