if it was his oesophagus then that would have been an easy one for the hospital to spot. From what you are saying, it sounds like he can drink at times and not at others....same with eating..... Things to think about are (off the top of my head) time of day, whether your brother is tired or upset....temperature of the food, amount of food, speed of eating, his posture when eating (sitting, lying, slumped) and whether one or more of these things cause eating or drinking problems.