I had ankle orif surgery 15 weeks ago, had an appointment with my ortho surgeon and x-rays today. he says its healed perfect, but why is there still swelling and inflammation?

Ask. Ask again.: He is probably right. The bones are probably perfectly healed. The soft tissue elements that help stabilize the ankle probably have not recovered enough to adequately do their job. Continued therapy and ankle wraps may be needed for a time. Swelling and inflammation mean healing is still going on, not necessarily an infection. Why not just ask the surgeon, after all, he knows best.