Severe lower back and left hip pain

I have had severe lower back pain for almost 2 yrs, I have actually had it longer than that but it got worse when I was about 6 or 7 months pregnant for my son and got even worse immediatley after having him in November of 08. I have been seeing a doctor for this pain and he has done multiple x-rays, and mris and told me that I am missing a disc between L4 and L5 and that I was born this way the bones are fused together and above L5 i have a slightly bulging disc. I also have something wrong with my SI joint and have severe muscle spasms in my back. They have had me on all sorts of muscle relaxers and I am now on soma 250mgs, I have been on vicoprofens, norcos, and am now back on regular vicoden 5/500mgs. The other stuff wasnt working and neither is the regular vicoden I am wondering if there are other pain medications that would help me manage through the day sleep at night but not be incoherent during the day as I have a 16month old and have to be alert. I know that this pain needs to go away it makes me cry during the day and night and I have a very hard time sleeping because it hurts so bad, PLEASE HELP ME FIND SOMETHING THAT WILL WORK. Not just for me but my family as well so they dont have to watch me suffer like this anymore.