Hi, My Friend Is A 66 Year Old Female Who

Hi,
My friend is a 66 year old female who is on Prestiq and Remeron for depression. She has significant swelling in her left leg and ankle and is beginning to swell in fingers. Swelling in right leg is resolved. Has developed significant pain in both shoulders, wrists, hips, knees and ankles. She is mobile, but stiff and walks slowly. Up to 4 months ago she was riding her horse, walking, asymptomatic with the exception of depression. Blood tests ruled out lupus and rheumatoid arthritis. Her heart functions are normal
What type of specialist should she see?