Listen to Dr. Dutch......
Itīs acute lumbago, probably the quadratus lumborum. Forget about heavy lifting for a while, do not try to `train around it` to soon. Taking antiinflammatories is a good idea, but be carefull with `a few aleves`, itīs bad to take more than the max. dosage. Some antispasmolytics like valium can be good as well. Itīs better to stay moving with painkillers than to stay immobile without them.
Heat-cold showers may feel good but wonīt do anything to speed up the healing. Massage wonīt help either, shitting around with tennisballs is oke if you want to look like an idiot, but are useless too.
Take care !