If you, at ANYTIME, experience numbness of your legs or your "saddle area" (any area of your body that would touch a saddle if you were sitting on it) get to an ER immediately. I had to have back surgery last year because my left leg went numb. I had had back problems ever since I got (shoot, forgot the name of it) whatever they call it when you are in labor and they put the needle in your back to block the pain from your waist down. That was 17 years ago. Since my surgery, I can do whatever I want. So much better.
I hope yours is just pulled muscles. One thing you can do if you don't have a heating pad is get an old sock (or new if you perfer), fill it with uncooked rice, tie the end shut and pop it in your microwave for about 45 seconds. It heats the rice up and makes a great heat pack. Also, take an antiinflammatory like Motrin or the generic.
Hope you feel better soon!