Thanks for posting here.
With your history I think your mother has got Calcinosis Cutis
. It can occur as a part of scieroderma. They are the deposits of calcium in the skin.
You have not mentioned ur mothers age.She is suffering from Mixed connective tissue
disease and you need to see a rheumatologist
and a dermatologist
team. Some safe painrelief measures can be undertaken to reduce the distress. Talk to the treating doctor about effective painrelief measures.
Take care of her.
Hope she will get better.
Dr shilpa bhat