There are many reasons for back pain and swollen feet. Possible causes include nephrotic syndrome, lower extremity venous thrombosis, and lumbar intervertebral disc herniation. 1. Nephrotic syndrome: it can lead to low back pain (pain in the kidney area), high blood pressure, body edema, hypoproteinemia, when the protein content in the blood decreases, it will lead to a decrease in the colloid osmotic pressure of the blood, which makes the fluid in the blood vessels flow to the tissue fluid, resulting in swelling of the top of the feet. 2. Lower extremity venous thrombosis: common long-term bedridden or lower extremity fracture, because of bedridden common symptoms of low back pain, lower extremity vascular embolism will lead to lower extremity blood reflux obstacles, the symptoms of swelling of the feet. 3. Lumbar intervertebral disc herniation: lumbar intervertebral disc herniation often has lumbar pain symptoms; herniation is serious, may be due to long-term compression of the nerve, resulting in lower limb muscle atrophy, blood reflux obstacles, causing swelling of the feet symptoms. There may be other reasons for the swelling of the feet and waist pain, and the swelling of the feet and waist pain should be taken seriously and promptly go to the hospital to get a clear diagnosis.