Hi I Got Into A Little Fight With A Friend

Hi I got into a little fight with a friend and he shoved me and I hit my lower right back into a bunk bed ladder, it's been 5 days and yet still when I turn, twist, or bend it will aggravate it and it feels as if it's a tearing sensation? Could this possibly be a broken bone or just a hurt muscle? If it's just a muscle what would you recommend doing? Should I stretch it and try to use it lightly or just completely try to avoid using it? Thank you!