Menu advice needed

Mark had been losing weight again and need some suggestions of meals that are easy to digest!! He has had a lot of antibiotics lately for urine infections and finds that after eating even a small meal he gets stomach pains and nausea. I have started him on the fortisip drinks again but he really wants to start enjoying food as he really doesn't have much else to look forward to. Tonight I am trying a bland meal to see if that helps. I am doing steamed fish, potatoes and vegetables. He can't have wheat, dairy, poultry or shellfish so that gets rid of a lot of things!
Thanks xx
Thanks xx