Low back pain and leg tingling?

Pinched Nerve. Low back pain going down the leg sounds like sciatica. This occurs when one of your lumbar spinal nerves is irritated. This can often improve on it's own, but if pain lasts greater than 2 weeks see your physician. There are many non-surgical options.
See a Doc. Could be a nerve root irritation in your back. See your doctor.
It depends. Tough question. Pain in lower back and tingling in the legs may or may not be related. You should see your doctor to have it evaluated, especially if this is a new symptom. If you have any changes in your bowel or bladder function, it is more of an emergency.

Related Questions

Low back pain and leg tingling at gym?

See a Doc. The first thing to do is to try to determine what activity brought about these symptoms. You really need to think hard about this. If you can identify what brought it about, then it may be helpful to speak to a personal trainer to see if you are using poor technique or if there is an activity that you are "overdoing". If the symptoms persist, probably best to see your doc or a back specialist.
Sciatica. Sounds like possibly sciatica. Seek treatment from pcp, orthopod or neurology. Can often be treated with therapy.

Had lower back pain x 1 wk. Also in buttocks. Better now but not gone. Now have tingling down one leg. Should it improve since back is improving

It may improve... Most cases of back pain will improve, especially with conservative therapies. However, the tingling down the leg indicates a nerve issue, the severity of which can only be determined with diagnostic testing such as MRI and/or EMG (best done 8 wks after symptom onset). It is possible to have isolated numbness/tingling of the leg without accompanied back pain.