plateau & inability to exercise :(

Hello!! I need help please. I recently had gastric a few month's ago (3/12/13) since then I have lost an amazing total of 100 pounds!! I feel absolutely wonderful. My only problem now is this plateau. I am afraid I am never going to get outta this rut! To quickly sum it up..I had back surgery a lil over 2years ago and in turn it made me even worse! I now walking with a cane as well. Does anbody have any suggestions? Does anyone know whether or not I will be stuckher because of lack of exercise? To give you an idea of the intensity of my pain, every time I try to do the pool therapy I get out of the pool with my legs shaking extremely bad! Idk what to do about being unable to work out. :( anyone know of anything I may be able to do?