Help! having horrible back issues?

I threw my back out really bad during this snow storm at the begining of the year...i was out there for about two hours shoveling and i guess my back just had enough. I most likely picked up way to much and lifted the wrong way. I ended up falling to my knees in pain and couldn't get up for about ten minutes. After about a week of recovering i was back to normal but later on i kept having trouble lifting things...i basically haven't been able to lift heavy things for the past couple months. Now im to a point where im putting on pants or loading small things into the dishwasher and my back gets close to being thrown out...also all the pain is in my lower back and when i do throw it out my butt sort of goes numb and the pain sometimes shoots down my legs. Im only 21...heavy chested and i have a tummy but not big enough to the point my back is in this bad of shape. I managed to pick an awful doctor who wouldn't listen to what i had to say when i tried explaining and i will be getting a new doctor, but i was curious if anybody has the same problem or may know whats going on because its bad if i cant even get my pants on :(