Kfox, did the siblings suckle this little boy when they were young? Sometimes babies will suckle genitals when they are searching for nipples. They can get significant damage if the urethra gets blocked or narrowed.
Sometimes baby squirrels will be ‘bed wetters’
and will soak themselves as babies. That is not the case with squirrels this size. That’s pretty unusual so treating with antibiotics would definitely be in order. Try to find an antibiotic. Ask friends and family. A single pill is sufficient.