My back is killing me...

Last monday I was working out in the yard picking up big rocks and moving them off my lawn. As I was pulling on one I yanked something in my back and it hurts sooo much! I can't find any relief sitting, standing, laying, it all sucks lol. I've never really hurt my back like this, and it doesn't feel too good. I also don't have medical insurance. How do I know if I hurt something important, like a herniated disc or something? Just looking for some insight because I never had this happen to me like this. Just hurts so much. I'm not one to complain constantly but I am starting to feel bad for my gf because all I seem to have on my mind lately is back pain complaints. Any suggestions would be appreciated like you would not believe...Just need some kind of escape from it.