Concord, N.H.—Tests confirmed Friday that a bleeding ulcer was the cause of New Hampshire Gov. Chris Sununu’s flu-like symptoms, his chief of staff said. Sununu was admitted to a hospital earlier in the day after having flu-like symptoms since Wednesday. He had tested negative three times for COVID-19. “Tests have confirmed that a bleeding ulcer caused the symptoms the Governor has been experiencing this week,” Chief of Staff Jayne Millerick said in a statement. “After blood transfusion today, he is doing much better. He is extremely grateful to the staff at Portsmouth Hospital for their outstanding care and to everyone who donates blood. As a blood donor himself, he is happy he paid it forward and grateful to all who do the same.” It was not immediately known how long Sununu would remain hospitalized. Sununu, a Republican, had said Wednesday he tested negative for COVID-19, hours after his office said …