I'm still a newbie at chickens, however I had a chick that at seven weeks started to walk funny and a leg twisted inward.
Two items of advice, the leg will need to be bonded if it is ever going to walk correctly and that has to happen quickly. There is some articles on BYC and the Internet how to make a leg splint. With the leg being swollen (and I know nothing about perosis, so I don't know if your chick has it or not) - if it is an infection - it does not take long for a chicken to go septic, so I would investigate so antibodics for little chicks.
I ended up putting my Oprah down at 14 weeks, as her leg deformity was treated to late (started treatment at 12 weeks - because I thought she had a vitamin deficiency and thought it would correct itself with correct high doses of vitamins/minerals) - however you have to correct that, it doesn't on its own. Somehow the leg deformity got infected too, maybe by a scrap she might have down early on when the problem first affected her leg at 7 weeks - anyways that turned into a small access which I treated right away, however the Tylan 50 never could stop the infection, and with time it turned into a big abscess. After reading several people's experience with leg deformities, I came to the conclusion that the long standing problem would not be correctable (hopeless another wards) - so I called the vet to put her down that night. When I went home, the entire leg was pretty hot to the touch, instead of just the joint, and I knew the battle was definitely being lost - and it would only have been a matter of time that Oprah would sub come to the infection. I felt so bad putting down my little fighter (she appeared that she wanted to live) - but this really was a downhill battle which was pretty painful at times, so having the vet euthanize her was a hard, yet very humane, thing to do. It was peaceful for her, and a tough learning experience for me.
I hope you can make him/her better. Best of luck to you and your new batch of chicks.