Unexplained swelling and pain in the feet is common in the following cases: 1, gouty arthritis or rheumatoid arthritis, for young patients with unexplained swelling and pain in the feet, you need to check the uric acid and rheumatoid complete set. Elevated uric acid and rheumatoid factor positive, often point to patients may suffer from gouty arthritis or rheumatoid arthritis, need to further to the rheumatology and immunology department for examination; 2, osteoarthritis, commonly found in middle-aged and elderly patients, patients themselves joint degeneration combined with mild to moderate osteoarthritis, the patient in the weather when the weather is warm there may be no obvious symptoms, when the air temperature drops, humidity increase or After long distance walking, swelling and pain in the feet will appear; 3. Some young patients who have trauma during strenuous exercise may have no obvious pain and discomfort during the day and then have obvious swelling in the ankle after sleeping at night. For this category, as long as there is no fracture or ligament injury, most of them can recover on their own after a short rest.