How to get rid of backpain within 15 hours?

I'm overweight, 5'2 and 280 pounds. I started having lower back pain and I don't know why. I think it was because I was playing with my puppy. It hurts so bad, I honeslty couldn't even reach my butt when I pee'd. Lol. I need help really bad. I have work tommorow, and I really need the money to pay my bills. I'm only 16 so please understand. My mom put heat rub and I have a heating pad over my lower back. Will this go away? I'm laying in a convave form because I know of have a hunchback. :p