My duck has a swollen hock/knee :(?

My duck (2 months) has a swollen hock. I think its bacterial infection but im not too sure. I read on the internet that i should give him injections from the vet but my dad wont let me go to the vet. So i was thinking about another alternative to heal his swollen knee. Can you suggest some please :) and i already placed a splint on his knee.