Sudden swelling and pain in the big toe joint could be gout or a bunion forming a bunion. Gout is characterized by redness, swelling and pain in the metatarsophalangeal joints of the first toe, increased uric acid in the blood, also known as hyperuricemia, and in more severe cases gout, gout stones, which are diagnosed by X-rays, and in severe gout, localized elevated masses may be present. A bunion is typically a deformity of the first toe with a reddened cystic lesion of the metatarsophalangeal joint, known as a bunion, which should be differentiated.