I agree with your vet's initial diagnosis of Trichomonas gallinae. Her symptoms match up quite well.
If you have a microscope, try mixing a small amount of very fresh feces with saline and looking at it under high power. If the feces are not very fresh, it's going to be unrewarding.
I would want to treat her again, possibly with something slightly different, and I'd want to treat all chickens in her posse. She may have re-infected herself, as this thing, while not terribly environmentally stable, can be easily passed around among a flock in the food and water, and can be subclinical so you may not see it anyone else. (I just posted about how I found a heavy infestation today in my own chickens while learning diagnostic techniques).
If you have a microscope, try mixing a small amount of very fresh feces with saline and looking at it under high power. If the feces are not very fresh, it's going to be unrewarding.
I would want to treat her again, possibly with something slightly different, and I'd want to treat all chickens in her posse. She may have re-infected herself, as this thing, while not terribly environmentally stable, can be easily passed around among a flock in the food and water, and can be subclinical so you may not see it anyone else. (I just posted about how I found a heavy infestation today in my own chickens while learning diagnostic techniques).