@ddljohn-- There are a lot of possible causes relating to the spine and nerves that could be causing it. It could be stenosis (narrowing of the spine), a pinched nerve or some kind of injury. It's just not possible to know without diagnostic testing.
If you're unable to get medical care right now, I would recommend rest (avoid bending or lifting anything heavy), and you can take pain relievers and apply heat to the area to relieve the symptoms for now. There are some back pain exercises too, but don't do anything until you see a doctor or you might make things worse.