Sudden pain in the foot, too painful to walk and not swollen, occurs for several reasons to be considered: First, acute gout attack: due to heavy drinking or heavy consumption of high purine foods such as seafood, it can cause a gradual accumulation of gout crystals. The pain in the metatarsophalangeal joint will often occur suddenly in the morning when you get up, and will be accompanied by significant functional limitations and inability to walk. Second, acute lumbar disc herniation: it may be due to an acute lumbar sprain when bending over to carry something, there is a lumbar disc herniation, compressing the nerve root, this time there will be acute pain and numbness of the foot. Third, increased intra-abdominal pressure: It may also be caused by increased intra-abdominal pressure such as bowel movements or coughing, and the herniated disc compresses the nerve, so it can lead to acute foot pain and the inability to walk.