Pulled muscles in the back usually improve with rest, stretching and anti-inflammatoy medicine (if you can take them) and physical therapy after a few days to weeks. Pulled muscles do not cause leg paralysis and therefore do not require a wheelchair.
The back injury may be more serious then a pulled muscle, such as fractured vertebral body (vertebral body compression fracture), injured back joints (facet arthropathy or facet joint syndrome), injured sacroiliac joint (SI), ruptured or damaged lumbar disk or slipped spine (spondylolithesis). These circumstances may require steroid injections or surgical treatments such as kyphoplasty or vertebroplasty, endoscopic rhizotomy, endoscopic discectomy or endoscopic fusion.
If the pain does not improve or if you have developed or develop neurological problems (difficulty walking, leg numbness, weakness or bowel and bladder difficulties then you should see your doctor right away. Good luck!