The animal "Clavamox" medicine is called "Augmentin" for humans.
Try typing in augmentin on your search engine, and see if u can find an online pharmacy . U will have a better chance this way.
I believe u will have a difficult time trying to find the clavamox brand name for animals on the internet WITHOUT a prescription from the vet.
I am sure I don't have to tell u , but I will anyway, you will need to make sure proper dosaging is adjusted , so that the dog gets the correct amount. Hopefully, your friend can remember the previous dosage the vet prescribed.
I am going on the assumption that clavamox was previously prescribed by a vet for this animal.
It is far superior to many other antibiotics, for treatment of skin infections, among other things in dogs.
I wouldn't advise your friend switching the type of antibiotic, if clavamox is known to work for this pet, for whatever condition ails him.