Eating - lost 40lbs already

My dad had triple bypass in february and he hasn't been able to eat since. MAYBE he eats 2-300 calories per day. We've tried just about everything, he complains about the same thing - everything tastes awful. Doctors told him to just "force himself" which he's trying to do now but it always results in vomiting. Lately he can't even smell foods w/o having to vomit - it's getting scarry... 40 lbs in about 6 weeks. He also has diabetes which might complicate things more. He gets incredible headaches after eating - I think it has to do with blood sugar but none of the doctors have a clue - not about the headache, loss of appetite, or vomiting... Any ideas?? -jr