1.Shoulder pain with swelling can occur because of many reasons.I would say visit a physiotherapist,under her guidance your mother will recover soon.
2.For weakness,(if she is not diabetic )give glucose water /pomegranate juice ,along with diet changes
3.Protein rich diets like Paneer,egg can be given
Next Steps
If weakness persist after diet changes , consult physician.
Health Tips
Ice pack for swelling