Jamie, swimming is a great way to recover. You are doing the right thing. I recovered from back surgery by swimming, and more recently, from plantar fasciitis and knee problems.
Swimming takes a lot of effort. I started out being winded after 2 laps and now I can swim a mile, no problem. And now that my feet and knees have healed up, I can even start to run, as well as hike for miles. Just keep at it, stay off the leg for a while, and walk again when you are no longer hurting.
You might want to observe other swimmer's form as you swim(goggles will help). You might want to read up on proper swimming form for the different strokes, or take a class. Form, and especially breathing, can make your swim easier and more effective.
Baxter State Park
55 years old, 5'4"
1/1/11 weight: 172 and grumpy
Lost 7 lbs on calories in, calories out
Went paleo/primal 1/1/12
Current weight: 144 and happy
Goal weight is 130 more or less