Why is there a foot swelling in a psoriasis patient for past two months?

Hello doctor,

The patient is my mother, age 58, with chronic psoriasis which is under control. She has been having right foot swelling for the past two months. Her left feet is normal. Initial diagnosis at local clinics was an infection and severe arthritis. She was put on anti-inflammatory, antibiotics and antifungal cream. There was some symptomatic relief but the swelling did not resolve. X-ray of her feet was reported mild bone degeneration. Otherwise no other significant pathology. She was admitted to the hospital two weeks ago. FBS, ESR and uric acid were reported as normal. She was put on cryotherapy and physiotherapy. She has been discharged to home now.

Her condition is slightly better but the pain and swelling did not resolve completely. She has a few more cycles of physiotherapy to follow. She remembers spraining her right feet two weeks before the entire episode of the swelling started. As she did not feel any pain or discomfort immediately after the incident, she just ignored the sprain incident. She also had a hysterectomy done two years ago due to calcified fibroids which caused occasional leg swelling at that time. Please advise what has to be done.