What could be causing crippling lower back pain? Would a girdle help?

See doctor. If you have back pain that is "crippling", then i would advise that you seek out a spine specialist immediately. There are many causes for severe back pain, and to give treatment options (including a girdle or corset) you need to have an appropriate diagnosis.
Many causes. There are many causes of back pain, most of them are due to various arthritic conditions although occasionally the causes can be more serious. If you have been having this pain for more than a few weeks you should really see a doctor who specializes in this area. These include, physiatrists, neurologists, orthopedist. Important to rule out anything of a very serious nature.