My dad is 59 years old.he bent down nd while getting up he got a catch in his lower back.he's in severe pain, lying down, can't move an inch.what is it?

Pinched Nerve/Muscle: Most times back pain that is sudden onset will resolve. He should use anti-inflammatory meds like ibuprofen, aleve around the clock and even tylenol (acetaminophen) to help. If this does not resolve he should see his doctor for a muscle relaxant as well. If it still does not resolve, i would recommend him to see a spine specialist for a full evaluation and testing. He may need to get an MRI to see inside.

Strain: Most commonly, sudden onset of "getting down" in the back is sacroiliac syndrome if one sided or lumbosacral strain if both sides or in middle. If does not go away within a reasonable amount of time, needs evaluation.