Discussion: See below...

"Throwing the medicine ball with my brother" might have done it.

Hope you feel better soon. Sore backs are terrible! Try putting a hot water bottle on it or even better a hot bath with Epsom salts and some light stretching in the bath.

Yeah, Macey said that to me tonight... That certainly would not have helped!
I ended up getting Steveo to rub the Voltaren gel in and give me a bit of a massage as well (:
Not sure if getting a sore neck was related or not but i had the hot wheat pack on that while i was getting ready for work yesterday and while eating dinner. It seems better today, although still a bit tender...

Sucks when that happens. Sounds like Voltaren and heat packs is helping! Keep stretching :P

And massages. They Iz good too. I think you should demand more of them to help you recover ;)