All poultry has cocci parasite in their poo.Cocci doesn't always present with blood in the poo. Bring a collection of her poo to a vet to do a fecal float and look for cocci and worms.
Tube feeding is good as if she gets too underweight then her organs will shut down.
What happens is they grow up & develop an immunity to it (there are several strains) and life goes on with the poultry living with the cocci.
Once they build an immunity, the cocci pass harmlessly through the gut.
They are always there, so doing a fecal test will always show there is cocci.
I have had this explained to me several times by vets, and it makes sense.
Otherwise, how do our older birds remain alive ?
Why are cocci not harming them ?
Cuz their immunal systems are aware of the buggers and do away with them before they can do any harm to the gut.