Thank you all so much for your replies (: I already took my little Yui to the vet and unfortunately her leg wont be able to be saved....
although on more positive news, she no longer seems to be in pain and stopped chewing on her leg, she's as active and playfull as before and is drinking and eating again. My vet explained that her leg is completely numb and will need to be amputated, however since yui doesnt chew on it or complain, the vet wants me to keep applying the ointment until the infection is less severe so she can perform the surgery, she assured me Yui will be fine as a three legged hamster and told me that right now for the next 3 days to apply the ointment, make sure she's in a safe cage with very few accessories and comfy bedding (which she adviced me to cut fleece in large peaces) mix vitamins in her water, give her chicken liver and shrimps and other hamster safe proteins mixed in her food for her to regain strength and weight and she injected some serum on her back to help Yui recover from not drinking much the last 2 days...im hoping everything will turn out ok, I love her so much and I feel awful that my lack of research caused her so much pain ):