Not knowing more about what happened it's hard to help. But if it's an injury it could be from jumping off roosts, etc. Brahma's are heavier so more likely for these injuries.
I would try putting her in a chicken sling (you can google for lots of examples, or search here, lots of posts) to see if that helps. It will take the weight off and let the leg rest. Just make sure she can reach food and water while in it. I'd add some electrolites and vitamins to her water. And then look at your set up for possible ways to lessen the impact on her legs. Lower roosts, more or softer bedding to land on, or anything she could have caught a foot or leg on. If she just tweaked it, it may be fine in a few days.
