Hi,
Diatomaceous earth isn't going to deworm her if you think that's her issue. Don't get me wrong as I have used that stuff faithfully for over 20 years, but not for something like this.
My first step for one acting in this manner would be to put her on some probiotics. You can give her a tablespoon or two of yogurt, or they make powders for their water. I'd also put Poultry Cell or Nutri-Drench or similar vitamins in her water. If she does have worms, they're tapping her and a vitamin boost will help her.
Here's some deworming info I bookmarked.
Valbazen (albendazole)
https://www.backyardchickens.com/ar...s-for-poultry-waterfowl-and-game-birds.75490/
Valbazen dosing is by weight.
undiluted at a dose of 0.08ml per pound of weight, given orally once, then repeated in 10 days.
Safeguard (fenbendazole)
Where to get if not available locally.
Jedds or Twin City Poultry
https://www.twincitypoultrysupplies.com/