Post-hernia surgery issues: unintentional 80+ lbs in 8 months

My 74 year old husband got UTI shortly after having surgery for hernia. Since then he has had 2 other UTI’s which were treated with antibiotics, the last one was a 6 week course. He has started eating less and less complaining about constipation at first but now diarrhea all the time. Doctors have done many tests, ultrasound, X-ray, CTscans, MRI, endoscopy, colonoscopy. The only finding has been C-diff but doctor says it is not active or producing toxins. He has lost over 70 pounds and is barely able to eat. He has been only getting a few hundred calories a day because he says it feels like the food gets stuck or makes him choke. His Gastroenterologist has him scheduled for Barium swallow with pill and Gastric emptying study but those don’t take place until 3 weeks from now. At this point he is skin and bones, loosing weight daily, is very weak and in the past few days doesn’t want me to leave him and becomes very anxious if I do go to the store or run errands. I am having a very hard time getting him to eat much of anything. We are experimenting with soups, smoothies, applesauce, soft scrambled eggs, protein drinks like Ensure, but he never can eat much of anything.