Her crop is a bit clay-like so I'm introducing some water to help clear it. She didn't come out of the coop this morning and her comb is more pale and shriveled than before. She definitely seems to be going downhill, poor old girl.
How old is your girl?
I'm sorry you didn't get a lot of answers from the vet.
The Ivermectin will take care of any external parasites, plus a few worms if she has any.
Does she still lay eggs? Feel between her legs for signs of swelling, bloat or fluid. A boggy crop can be a
symptom of an underlying condition like reproductive disorders, coccidiosis overload, infection and worms. Internal laying, Egg Yolk Peritonitis, cancer, tumors, etc. are unfortunately common in laying hens and they start to decline-sometimes they do not preen or dust bath like they should which then lends to dry skin, unkempt feathers and general unwell look.
See if you can get the crop to clear. I usually start with Poultry Nutri-Drench at 1cc per 3lbs of weight direct dose and give coconut oil (organic unprocessed is greedily eaten). Massage the crop to help loosen up the contents and see that she is drinking. Some people separate the hen for treatment - that is your choice, but I find mine do much better when they can stay with the flock. Massage the crop several times a day if you can and get more water into her. If the crop is still boggy after a couple of days of water, coconut oil and poultry vitamins and soft food (hard boiled egg, wet feed), then I move to the next step of giving 1 stool softener capsule (stimulant free). Still plenty of water, the nutri-drench and massage.
Getting a necropsy is always a good idea if you lose her.
Each of us have our on method of treating the crop - both articles below have very good information, you may want to read those.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
http://www.backyardchickens.com/a/impacted-slow-and-sour-crops-prevention-and-treatments