Oh, okay, I think I can picture it now. It's like the tendons are too lax, so she walking back on her heels.
I wish I could offer more advice but it is really out of my area of expertise. My foal was born with a deformed cannon bone, so I researched foal leg issues a bit, but not enough to offer advice.
It is my impression that lax tendons get stronger over time, but I don't want to tell you that because I honestly have no experience with it. I did Google "foal lax tendons" on image search and found this photo/article.
Is this what you foal has? Checking Over the Newborn Foal: What to Look for in a Healthy Foal | Suite101.com
PS. My vet recommended increasing
the exercise with my foal to strengthen his leg. (I don't have pasture, so I would ride his mom around the property and let him run around and follow). So maybe the opinion of a vet would be a good idea. Limiting turnout almost seems counter-intuitive to me. But I am just a horse owner, not a farrier or vet.