My back has been in pain for 6 months! Please help me?

Ok this is my story. I have been having back pain for the last 6 months. I have gone for x-rays and mri scans and they tell me that my lower lumbar has an exaggerated curve in it. I row 8 times a week and I can't miss any training because of it. I want to row for my country next year and I will not give up. I went to the doctor who then sent me to the physiotherapist. I have been going to a physiotherapist for around 3 months. All he has given me are crappy stretches and things like that and they are doing nothing. Somebody PLEASE help me?