What have i done to my leg?

I was walking home from school today and suddenly my left leg began to hurt. I know that sounds really stupid, but it's the truth and that's what happened. I wasn't able to walk on it and had to hold onto my friends shoulder and hop-along. It's really quite bad at the moment. I'm unable to put any weight on it and i'm having to hop about the house. It's almost as if i've pulled the actual hip or one of my hip flexies inside. Whenever i do put weight on it, the pains really bad and my leg almost buckles beneath it. All i know is that it's really painful and do you think it'll be better by morning?