Most lower back problems are caused by ligament damage. The pain in the area causes local muscle spasm, hence the hardness at the base of L5 and this eventually can cause refered symptoms into the leg(s). The usual forms of effective treatment includes spinal mobilisation and manipulation + or - TENS, Laser, Ultra Sound, Lumbar traction, even local heat via Hot Packs, Short Wave Diathermy or Micro Wave. Some of these are old fashioned and some Physios may not use them. When you are not at the right Physio getting it fixed, your best friend is a hot pack.