I'm a 20-year-old girl, and my back hurts the afternoon before yesterday.

Back pain may be caused by kidney stones, nephrotic syndrome, glomerulonephritis, ureteral stones, etc., but it cannot be ruled out that it is caused by lumbar muscle strain, lumbar disc herniation, lumbar sprain, etc. It is recommended to check the cause, if it is caused by lumbar muscle strain, it needs to be relieved by massage or massage.