Bo went to Brian LGH, Which if you live or have ever lived in Lincoln, you know Bryan LGH is closer to UNL. They already said Bo went home, now if he had something serious like a stroke or heart attack, they wouldn't have released him the same day he was admitted.
As average everyday folks, we catch the flu and can take some time off. I don't think Bo can afford that kind of luxury, plus we can all agree Bo can be stubborn. I'm sure with how busy he has been during the week and prepping for the game, put a flu on top of it and its understandable how Bo's health would go downhill like that.
Hope he takes the night off to get some rest and stay up watching film like Beck and JP said he might do.