I have this pain in my right side of back after i fell i het the door knob he hurt then but the pain stop it was bruss real bad a across my back now the pain is back?

Back injury: If you struck that spot in your back, a bone and/or muscle bruise is likely. Look for black and blue discoloration developing in a day or so. You may have also strained your back if you twisted it when you fell. Apply cold compresses and rest your back. You can take Tylenol or anti-inflammatory medications like Advil or Aleve. See a physician if there is severe or worsening pain.