Suggest Treatment For Knee Arthritis

My sister spent 2 weeks in hospital for treatment of a heart condition (fluid in the lungs) and a couple of diabetic foot ulcers. She was placed on prevastatin and water pills and discharged. She also has arthritis is both knees and back. She believes the statin med has dramatically increased her joint and body pain. Now, she has a problem eating, she takes small portions of food and cannot finish, she also states that everything has a sour taste and she cannot eat much at all. While in the hospital, she could not eat anything given to her, (you know, terrible hospital food!). Could having not eaten very much for 2 weeks affected her stomach?, and why all of a sudden, is all food tasting sour?