In the middle of my lower back it feels like it is pushing downward so bad that my legs feel like they are going to give out. feels like crushing pain?

?disc, facet jcts,?: The cause could be discogenic (e.g. herniated discs), disc dessication (disc degeneration allowing the vertebral body above to touch or approach the one below), or facet joint inflammation, all of which could cause nerve root pressure resulting in your leg symptoms. You need eval and treatment by an orthopedic surgeon. Get an MRI of the lumbar spine.