Replying to Sprained Back

So I sprained my back skiing saturday and it fucking sucks. I went to ER and the only thing they said they could do for me was give me vicodin and valium and wait until it starts feeling better. Theres a comp in my area this saturday that I was set on doing and I'm thinking about just taking enough drugs so it doesn't hurt and then trying to compete. Has anyone been in a similar situation? The only thing I'm worried about is hurting my back more, but since it's just a sprain I don't think any long term damage can come of it. Any thoughts?