I Was Pushing A King-sized Bed Forward With My Knees

I was pushing a king-sized bed forward with my knees slightly bent, using my knees and hands. I heard (and felt!) a "pop" in the small of my back which caused acute pain that lasted for several minutes. (Worst pain I have ever experienced with the exception of childbirth.) It happened about 90 minutes ago. I have applied ice for 20 minutes X2 and am about to apply heat. It is painful to bend from the waist and there is dull throbbing pain in the small of my back radiating out to the left and right. No acute pain at this time and the area is not painful to touch. I have never had back surgery or been treated for back pain. Thanks for any advice you can provide. Joanne