I don't see anything wrong in her feet, I think this is likely a niacin issue
I don't think we are going to get an answer on whether or not the b complex you have currently is good to give orally, so could you access the durvet brand b complex from TSC? If you can, I'd start it ASAP 1 ml per day, if not I'd get her on niacin capsules. Flush effect ones, not flush free/no flush. Empty the powder from the capsule into her drinking water, I don't recall the dosage I used but I'd say about 100mg capsule for a gallon of water for now. You can get the niacin capsules from online or from a health store.
I did this for one of mine when she was really unwell with a niacin deficiency, it worked great but it took a week or more to start seeing real change. The extra niacin won't hurt any other ducks- they should poop out any excess that they don't need.
Keep a close eye on her legs, niacin deficiencies can make leg injuries more likely, you have to be extra watchful for their tendons as they can slip out of place and would need slipping back in before they heal in the wrong position. You should be able to find old forum threads about this. I don't think it's likely, but it's worth looking into. In the meantime, start that niacin or b complex asap