If very young then a drop at a time right inside the bill let them swallow before doing it again. Never shoot any liquid down their throats too easy for them to aspirate. If you have mealworms you can also try putting the B complex over them if younger than 2 weeks I crush them in my hand before...
Plus some things are just very hard to diagnose. Since most lameness and hobbling usually means a niacin deficiency and then we put them on B Complex it and nothing changes makes you wonder what else is going on.This link talks about Rickets in chickens but i wonder if getting the supplement...
Warm water therapy is so good for them even if just 5 mins let them swim around with supervision then pat dry and right back under heat. They will love it.The water just deep enough they can swim and still stand up if they want. I forgot to mention the water helps to take pressure off the legs...
I can’t think of anything other than niacin deficiency. Was she like this when you brought her home? I would def keep up with what you’re doing. Are you also giving warm water therapy?
Have you watched them eat the pellets okay? I usually don't start my ducklings on pellets that young.This add on is a perfect way to administer liquid meds I bought it from Chris Squirrels which is closed now but there should be other places that sell them. She definitely needs the liquid B...