Severe itching and bone and muscle pain

My mom suffers from pain in the back of the neck and the left houlder (it's more in the joints). Her spine is also painful or at best sensitive. The pain never goes away but it's usually stronger from the evening onward. She cannot have any spices sinces 2012, gives her severe itching, even in the eyes! Same thing with chocolate. But even when avoiding those foods she can still get itching from unidentified foods. The itching is very pronounced on the lower chest (left side) and over the spleen. Her skin in super sensitive especially on her crown and face and in summer she gets sweaty all over her face and head and neck which can itch and lead to eczema like skin reactions. She suffers from severe pills and constipation that have been present for many decades and cannot have a bowl movement without laxatives. She used to get muscle cramps but it seems a little less frequent now.
The most disturbing symtoms are the skin reactions and the itching as well as the painful neck, shoulder and spine. What remedy do you suggest to relieve her?
FYI, she is 83.
Many thanks
Sarah