Weight Gain

Been looking at weight gain sites to get ideas of foods that I could eat to try and boost my weight. Due to horrendous stomach problems, not bacteriological problems, having trouble eating so am losing weight. Dialysis uses about 400 calories per session but all I want to do is drink instead of eating and of course that is not good for me either! Really fed up with the whole thing. Sometimes just looking at food blows my stomach into three times its normal size. Is it the kidney failure, having cystic fibrosis or the cocktail of drugs I'm on? Blessed if I know.