Never feel full - hurt across back

I had my first lap band in January of 2007 and lost 70 lbs. I kept a steady weight until March of 2010. At this time, I had my fluid removed to have a scope done. When I went back in to have the band tightened, I had problems. I couldn't even keep water down. I had the fluid removed and the doctor ordered an upper GI. I had a slippage and had the band replaced in August of this year. Since having the band replaced I have gained 20 pounds and feel no restriction. I never feel full, but I often have pain across my back. Sometimes I feel like my chest cavity is expanding (my bra gets too tight ), but I don't feel like my stomach is full. Has anyone else experienced anything like this? It is very frustrating since I had such success with the first one. I feel like my doctor is not taking me seriously, but I know it doesn't feel like it did before. I am self pay (twice) and can't afford to have it done again.