What workouts can I do while I am injured??

I am a college rower and have had lower back pain for a while.  It has been getting progressively worse and about a month ago, we had a really had workout and ever since that day my back hurts so bad that i can't row anymore.  It feels better than it did at its worst, but it still hurts and I still cant row.  It has been over a month since I have worked out and I am going crazy.  I have tried riding a bike and getting on the eliptical, but my back seems to hurt way more the next day so I am reluctant to do anything.  I have an appointment with a back dr in 2 weeks but I really want to do some kind of physical activity so I can stay somewhat fit.  Any suggestions?