We turn next here to former president George H.W. Bush, in the hospital tonight, just days after saying farewell to his beloved Barbara. ABC's Matt Gutman from Houston with what we've learned tonight. Reporter: The president falling ill barely a day after his wife Barbara's funeral. That infection spreading to his blood. What's called sepsis can be fatal. On Friday, the elder president bush gamely greeted hundreds of mourners. The next day, his wife's funeral. The 41st president wheeled down the aisle towards his wife's waiting casket by the 43rd president, his son George W. Bush. Even taking this picture with three other presidents. His other son, Jeb, describing his parents' undying love. He held my mom's hand all day long yesterday, and I called him and he said, "I'm kind of a cry baby right now, I'm not feeling very good." Reporter: A parkinson's-type disease has kept the president bound to a wheelchair. But that didn't stop him from sky diving on his 90th birthday, rewarded afterwards with this peck on the lips from his worried wife. Though full of vitality, famously throwing out first pitches at baseball games, the elder bush was twice admitted to the hospital for pneumonia last year. Always cared for by his wife, Barbara. And so let's get to Matt Gutman, live from Houston tonight. And Matt, obviously, so many tonight talking about that marriage of 73 years, and the impact her loss could be having on his health, as well. Reporter: Could be a huge impact, David. Now, we spoke to president bush's representatives tonight, they say that he is responding to this aggressive treatment to that sepsis by his doctors, but there is one ailment they simply cannot treat, that is the so-called broken heart syndrome. This is the first crisis in president bush's entire adult life that he is dealing with without his beloved Barbara by his side. David? So true, Matt. But he's proven over and over again what a fighter he is, and we know you'll stay there on the scene for us. Matt, thank you.