Sorry this reply is long, but I want to be detailed.
I have bachelor of science in sports medicine and a doctorate in physical therapy. I currently specialize in treating orthopedic and sports related injuries from the amateur to the professional athlete, as well as the every day average joe. Having said that, the following is only my opinion and not medical advice being that I have not evaluated you and I am not your health care provider (have to say that for legal reasons).
First of all based on your description of the mechanism of injury and coinciding symptoms you have done one of two things: 1) strained a intrinsic (stabilizing) muscle in your lumbar spine which is now inflamed and putting pressure on one of your lumbar nerve roots. 2) injured a lumbar disc which is now either bulging or herniated and again putting pressure on one of your lumbar nerve roots.
Pressure on the nerve root is what is causing the pain to shoot down your leg, and until this pressure is removed your pain and discomfort will not subside.
As for how to deal with this injury.
Rest, give yourself 1-3 days of inactivity/rest to let things settle down.
Ice your low back 2-3x/day for 20-30 minutes each time to calm inflammation.
Take anti-inflammatories (Ibuprofen
or Naproxen) 2x/day for 7-10 days, again to calm inflammation. Legal statement: Check with your doctor before taking any medications.
4)Perform GENTLE, PAINFREE low back, and leg stretches.
5)If symptoms DO NOT subside in 3 days make an appointment with your doctor, preferably an orthopedic specialist and get them to prescribe physical therapy. They also may need to have an MRI done to diagnose disc pathology (x-ray will not see this). If disc issue is present or severe pain persists doctor may give you an epidural (shot in spine to block pain and reduce inflammation).
Many people have suggested that you see a chiropractor. I have nothing against chiropractors, they definitely have their place. But getting an adjustment when there is a possible disc issue is simply not a good idea. Your need to relieve pressure in the area, calm inflamation, and strengthen the weak stabilization muscle in your spine in order to prevent reoccurrence of this condition. The movement you felt in your back was likely one of your vertabrae moving due to fatigue/weakness of associated stabilizing muscles (specifically your multifidae).
And by the way DEFINITELY DO NOT SEE A PODIATRIST, this has nothing to do with your feet.
Hope this helped. If you have any more questions let me know. Good luck