If a patient has severe back pain after a cold, there are several reasons as follows: 1. The most common reason, the body will be infected by bacteria, viruses, fungi and atypical pathogenic microorganisms, such as mycoplasma and chlamydia, during the infection, the pathogenic microorganisms will release endogenous pyrogens in the body, such as tumor necrosis factor, interleukins, leukotrienes, bradykinin, prostacyclin and so on. These substances will lead to muscle aches and pains in the body, especially in the lower back, knee joints and other joints, where there is a great deal of pain. 2. For patients who have had a herniated lumbar disc or bulging lumbar disc in the past, there will be a significant increase in back pain after a cold. Because of the transient activity of rheumatic factor in the patient’s body, the situation of severe back pain will occur.