This is the big one. Just about any thing can trigger off a lower back. Typically there is an underlying strain pattern that your body has been able to keep a lid on, then wham some small insignificant event like turning in bed or reaching for a cup of tea and your back spazzes out on you. Of course there are other events like heavy lifts and accidents and any number of other things that will cause any thing from an ache to a full blown meltdown. This is usually the result of a gradual shrink wrap of our muscles slowly decreasing your flexibility and increasing your susceptibility to injury. This shrink wrap starts locking up the vertebrae in your lower back which markedly increases your chances of a lower back meltdown. Unless there is a significant degenerative condition it is pretty easy to get your lower back in good working order again. It's best to go to your osteopath and get a diagnosis and every thing working properly and then get into the SFL exercises. You can never stretch yourself as well as some one else can so check out the assisted stretches and see if you can train some one up to help. I use these very same exercises on my patients and they really work. Of course there may be a requirement to strengthen your core muscles to help hold everything together.