After a girl has sex, there may be back pain, which is also a normal phenomenon. If a normal person does not have back pain after intercourse very often, if the normal frequency of intercourse, there may be some basic diseases of the lumbar spine, consider whether there is lumbar muscle strain, whether there is a herniated disc, whether there is inflammation of the lumbar spine, if there is back pain under frequent intercourse, it means that this thing is done too often, it must be moderated, in order to achieve good relief. The back pain can be relieved by moderation.