Feeling fever in the calf, the first thing to note is whether there is a herniated lumbar disc. The most common clinical condition is a herniated lumbar disc compressing a nerve, resulting in radiating pain or numbness in the muscles of the innervated area, sometimes described by the patient as fever. In the case of lumbar 45 disc herniation compressing the lumbar 5 nerve root, there will be radiating pain in areas such as the posterior or lateral calf or medial dorsum of the foot, sometimes combined with numbness. In the case of lumbar 5 sacral 1 disc herniation compressing the sacral 1 nerve root, there will be radiating pain or numbness in the area of the posterior aspect of the calf, the lateral aspect of the heel and the sole of the foot. If the compression is prolonged and the nerve becomes ischemic, degenerative, or necrotic, a numbness in the area of innervation will occur, and sometimes the numbness combined with pain will be described by the patient as fever.