The specific causes of sudden swelling and pain in the feet are as follows: 1. Gout: When gout attacks, there can be sudden pain in the joints of the feet, most commonly at the root of the big toe, which is accompanied by swelling and pain as well as redness of the skin and elevated skin temperature, which should be diagnosed with the patient’s medical history and blood uric acid tests, 2, infection: for example, the foot bacteria and tuberculosis infection suddenly aggravated, the foot can have a sudden swelling and pain, accompanied by local skin temperature rise, then we should do blood tests, pathogenic examination, while taking foot x-ray, CT, MRI for diagnosis and early treatment.