I Have Pain On Both Sides Of My Right Knew.

I have pain on both sides of my right knew. It is moderately painful to walk. Sitting for extended period makes it worse. Some days it is better than others. At times it has stiffened and once it cramped. I am 61 and approximately 40lbs overweight (76"/260lbs) I walk an overage of 3 to 7 miles per day (per Fitbit) depending on work requirements, primarily. Should I see a doctor, and if so what specialty?