What Causes Stiffness In Muscles Along With Swelling?

for several days my leg has been swelling, which it often does due to arthritis, but this is different it feels as though the muscles or ligaments are tightening so much it is actually difficult to bend my leg, and it feels heavy, I have tried keeping it up for days and using ibuprofen, but seems to be getting worse, never had the leg feel so tight and painful