What Would Be Wrong If My Left Leg Goes Numb Sometimes?

Sounds like a pinched sciatic nerve on the left side in&tbsp;the&tbsp;lower lumbar region of your spine.
The human body has two sciatic nerves, one connected&tbsp;on each side,&tbsp;that run from the lower part of your spine, down the legs and into the feet.
They are the biggest nerves in the body and will cause numbness in the legs and sometimes in the feet if one or both are pinched.
This is usually caused by&tbsp;one or more&tbsp;ruptured discs, which sit in- between&tbsp;the vertebrae of the spine. Standing for long periods of time can aggravate the situation.
If it persists, you may want to think about seeing a neurologist or an orthopedic doctor.

The numbness in any part of the body is not good sign. The numbness in legs can be due to

1. Trauma or injury on back
2. lumbar sacral stenosis. (pinched nerve)
3. disc prolapse
   
4. Seizures
   
5. Multiple sclerosis
6. Diabetes
7. stroke

Have MRI brain and spine for differential diagnosis