Consider rheumatoid arthritis, gout, lower extremity venous thrombosis, cellulitis and other causes of leg pain and swelling. 1. Rheumatoid arthritis: symmetrical swelling of joints, pain, morning stiffness, limited joint movement, markedly elevated rheumatoid factor and blood sedimentation. 2. Gout: sudden redness, swelling and pain in the joints, localized skin fever, and markedly elevated uric acid in laboratory tests. 3. Lower extremity venous thrombosis: due to thrombus dislodgement and blockage of lower extremity veins, there is sudden leg swelling, accompanied by distension and pain, which can be clearly diagnosed by lower extremity vascular ultrasound. 4. Cellulitis: mainly for the calf local redness, pain, swelling of the surrounding tissues, under the guidance of the doctor to apply erythromycin capsules, local ultraviolet light treatment can reduce. There are many possible causes of leg pain and swelling, you need to go to the hospital to check and clarify the cause of the disease for treatment.