My lower back is in excruciating pain! if i bend over even a little, i drop at the waist & have to push myself back up by my knees! what could it be?

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