back pain after surgury gotten worse and continuing

I had lower back surgery 18 months ago because my Dr. after one vesit told me that the fusion to L5-S1 was all that could help me with the back pain I was having. I also told the Dr. that I did not have any leg pain. After the surgery the pain in my back has gotten worse and is continuing to do so. I can not find a Dr. that has been able to tell me what is wrong, they (being 5) have all come up with drifferent diagnosis. I have loss the ability to even work (I was layed off because the pain will get so bad I will just fall). Has anyone had this happen after surgury? If so what was wrong?