How long should I give a sprained lower back to heal?
First, let me just say what I'm experiencing in case anybody with experience can elaborate as to what happened:
One day about 3 weeks ago I was doing my warmup set with squats. I didn't round my back or perform any jerky movements but all of a sudden on the way down my lower back muscles started hurting bad. Not agonizing or shooting pain, but I knew something was wrong. However unlike the pain and inflexibility I get if I pulled the bar up with my lower back using bad form, I was able to bend over without tightness, just a mild to medium discomfort. A week later the pain came back when I was doing cable rows and my lower back was just tight isometrically. I haven't done either exercise since then and just have some hints of pain here and there, like when I get up from sitting and start walking. Goes away in a second or two. Also it hurts when I start coughing (getting over a cold). Judging from this I don't think it's a disc problem but rather a sprain or something with my lower back muscles.
Second, if that is what's going on, what should I be doing about it besides avoiding any exercise that utilizes the lower back even isometrically? How long should I wait until attempting to give it another go?