Most hens will swallow a human calcium citrate with vitamin d tablet whole. If it is large or using Tums, you can break it in two and give it. Epsom salts or warm water soaks are okay once if the chicken is healthy and not lethargic or very weak. Soaking a really weak chicken can put them over...
The normal dosage of calcium is around 600 mg, and many times 300 mg per day is plenty. I think she has had more than she needs. Does it look like an egg shell or possibly lash egg material. Can you lubricate the vent wit a little oil, and place her in a warm spot on a clean towel?