It sounds as if you might have trapped a nerve or blood vessel in the lower back. Tingling, numbness and burning are sensations that can arise from interrupting blood supply, starving the nerves lower down of oxygen.
Strains are overuse of the muscles or the tendons that connect them to the ends of the bones and, yes, lifting kids will have this effect.
However, if you are stressed, the lower back (and shoulders) are areas especially liable to be stiff as you hold yourself in a state of 'tetany' when all tense. It's a bit like a coiled spring. When muscles are tense, they are shorter and easier to tear or strain under load.
There are a few remedies to consider, please choose what describes your situation best:
- Atrogel® and Atrosan® together for temporary bouts of stiffness.
- The mineral magnesium (go for a liquid form for better absorption): 300-400mg a day, to help relax tense muscles.
- Daytime Stress relief. This is a mixture of Valerian and Hops which can take the 'edge' off anxiety very nicely but without leaving you drowsy. It might well help you get off to sleep better too, which in turn helps reduce pain perception.