Hi, I Have Been Suffering With First With Pain On

Hi, I have been suffering with first with pain on the side of my knee. Had a shot of Cortizone which seem to help for a short while. Now both of my knees are stiff, it's difficult to go up and down the stairs and my legs both of them ache most of the time. When I get up to walk and my legs are very weak and Steph until I get moving then it gets a little better but the knees remain stiff