Julie - lost a lot of weight after having 9 hour operation for duodenal cancer. I haven't managed to put any weight back on and now have pain in other areas

Hi, I had duodenal cancer and had a 9 hour big operation in Feb. I lost almost 4 stone in weight. I haven't been able to put any back on. I'm now getting intermittent pain in my lower ribs and spine. So, worried it might have gone to my bones!