M/20. had feelings of heaviness and altered sensation in left leg for a year now, off and on. i'm scared of als. seen a nuero and my gp that said nothing is wrong. but what could this be? my anxiety?

Definitely not ALS: Can be many things including anxiety, but you definitely don't have ALS as this illness does not cause altered sensation, it's a purely motor syndrome. It can be a pinched nerve especially if you have lower back discomfort, best check with your doctor again.

It seems that: You need to consider talking with a psychologist. Anxiety can lead to physical complaints. Here's a blog that explains how some people take things out on their bodies. Sometimes the symptoms ; language associated to the symptoms are clues to the causes. http://wakeupanddreamcatalyst.blogspot.com/2014/03/tuesdays-psychology-tips-do-you-take.html.