I was sort of plateauing as well, and my trainer suggested lowering my calories by a 100 a day to 1400. I am not sure if this is manageable for your RDI, but it seemed to give me a bit of kick-start. Also, if I accidentally go a bit over, I am still under 1500, instead of going a bit over on 1500, and making it close to 1600. But otherwise - sorry to hear about your back issue.