Can you take her to a vet?
Do you feel fluid/water in the abdomen?
What symptoms does she exhibit - lethargy, labored breathing, difficulty walking, not laying eggs, crop issues, watery/loose stools, weight loss?
If she has fluid in the belly - Ascites, there generally is an underlying condition - reproductive disorders (Egg Yolk Peritonitis, Internal Laying, Salpingitis, cancer, tumors, etc.) and/or organ dysfunction/disorder (heart, liver disease).
If she is having difficulty, you can try draining her to remove some fluid to make her more comfortable. Antibiotics to help control infection may be needed as well. With Ascites and reproductive problems, treatment results can be short lived, infection can set in or draining needs to be repeated periodically. Some birds can live a good while with these conditions, while others decline regardless of treatment and supportive care.
If the Ascites is associated with reproductive problems like Internal Laying or Egg Yolk Peritonitis, if you have vet care and an can afford it. Suprelorin implants to stop ovulation may be an option for you - that would need to be discussed with your vet.
https://poultrykeeper.com/reproductive-system-problems/suprelorin-implant-for-chickens/
I do not know much about herbal or natural remedies for chickens.
@coach723 has used them before with her flock. Here's a link to one of her posts, hopefully she will chime in with her thoughts.
https://www.backyardchickens.com/th...breath-if-you-hold-her.1284253/#post-20750855
Here's another link you might find helpful if you are looking for alternative methods of care:
https://www.fresheggsdaily.com/2017/06/water-belly-or-ascites-in-backyard.html