Thank you for the responses! I thought Hypercium was another name for St John's Wort but apparently not. Rather I see it is a homeopathic remedy made from St. John's Wort.
So, I ordered some Hypercium 30 on Amazon- they didn't have any at our local health food co-op. Maybe I should take the St. John's Wort myself as I have been upset the last couple days over this hen, and fearing what might happen to my flock, and also the flock of a nice person to whom I re-homed a few of my Swedish Flower Hen chicks.

May try cranberry in the interim as it may take awhile to ship the hypercium. Chickat, I am very sorry for your loss.
Also, I am giving infant vitamins (PolyViSol) 2-3 drops, applied to side of beak, just in case it isn't Marek's but a riboflavin deficiency, which I hear can cause similar symptoms.
Gosh I want this hen to live. I really like her- she's a sweetheart, and she's pretty, and she's a hen.
Thanks again folks!