This discussion has many helpful comments I would have made. The 5 Day Extended Patch Test identifed my allergens, yet from the helpful photos I don't see how that is possible at this time because the entire upper back and some of the mid back torso must be clear of rashes to perform the test.
If she has Allergic Contact Dermatitis, ACD, which I do and is a common form of eczema which often manifests itself in middle age because of body rebels against substances, both natural and created, which it feels is toxic to us. It raises up our histamine armies to try to rid our bodies of them. These histamines raise our inflamation causes rash, internal and external itch and pain.
Jennifer made an interesting comment about possible metal allergies. Although the patch test can test for metals another form of testing is also used for blood. Medicare paid over $1,500 each time I was given the 5 Day Extended Patch test, however, they would not pay for the blood test before my scheduled TKR. I had to pay $600 out of pocket for the results which resulted in me having to cancel my surgery. I was allergic to over 6 metals, although not allergic to titanium the Orthopedic Surgeon said that even titanium had traces of other metals and in time with use the metals in the implants will slough off metal, thus entering the blood stream causing these metals, a poison if allergic, to course though our bodies..
My ACD was severe and I was able to control my external rashes with elimination of certain contacts. However I still had issues with internal inflamation which caused stinging, itching and burning under my skin, all over my body without rash. I know you tried steroids, but not sure if your mom tried injections. With the Cortico-Steroid Kenalog 40 injection I could eliminate these internal skin sensations for 9 months. However, 2 months after getting the injection I would have significate hair loss for 2 months, then it would regrow.
I eliminationed the need for these injections 3 years ago- I finally broke down and attempted an anti-inflamation diet. Mainly giving up all processed sugar and minimizing natural sugars. Durng the 2 month detox I also gave up gluten. Read this short, easy to understand book which explains it, The Yeast Connection Handbook, by William Crooke, MD. I didn't have external yeast infections on the body or vagina, it's what is going inside our intestines with the living yeast colonies we all have. Amazon still sells this book. Dr Crooke was a pioneer in the field believing sugar and gluten fed the yeast in our bodies which raise histamines. Today I follow the maintanence and still never eat processed sugar, but have several servings of fruit and have found I do fine eating gluten. Still to this day no retain of my internal misery which was leading me contemplate suicide because my misery was so great.
Right now I am sure you have attempted to detox any allergens, just guessing Only use Grandma's Lye Bar Soap. It's 2 ingredients are lye and lard. The lye is converted into glycerin in the soap making process . Google their site and all will be explained. It's moisturizing Try this as a shampoo if the scalp is itchy. A good safe shampoo is VMV Clark Wash. Both of these products are sold on Amazon.
Avoid all blended materials. Rubber is a common allergen. We know latex comes from rubber but also is a host of other elements. MBT is one that is used to blend materials and create elastic (yep, no elastic in bras and so on) and memory foam. It accelorates blended materials like poly cotton. Make sure beddding is free of all memory foam (that is what set off my total body eczema), even if it is covered with 100% cotton it off gasses. It can be covered with plastic then cotton if the bed or pillow can't be replaced. All blankets must be 100% cotton or 100% polyester. Do not walk of floors barefooted as shoes containing MBT or other rubber elements have contaminated it. I can only wear plastic, vinyl or 100% leather footwear without first putting on a 100% cotton sock, plastic bag, elastic sock to hold it up and then the shoe. Many cannot wear leather if formaldahyde is used to tan it.
No wrinkle free or Scotch Guarded or fire retardart fabrics as these are treated with common allergic chemicals.
No fragrance.
Check into blood chelation to remove metals from your blood, however I do it naturally drinking 1/2 bunch of blended cilantro for a few months daily then back off for months and repeat. Cilantro is a natural way to chelate blood. Google it. On a Mayo's Grovers Disease skin discussion site I learned about this. Beside ACD I have another form of eczema Grovers Disease, GD aka, Transcient Acantholytic Dermatitis, TAD. Many of us found that detoxing our metals put this into remission. Heavy metals, which we all have accumulated are now tied to Alzeheimers, Parkinsons and Grovers Disease. Google it. I'm not saying drinking blended cilantro is pleasant, but I consider it a tonic and simply do it.
I was tested for a hundred different elements and identifing my allergens, going on an anti-inflamation diet (which I will stay on for life because of the results) and naturally chelating my blood has allowed me to resume a normal life. Yes it is a bother, but to live without the pain and itch of eczema makes all the trouble worth it.
Like others I am very sympathetic. I know and have felt your mother's misery. I know in the future it may return, eczema is chronic. Please follow up with any new information about her conditon.