Dog With HGE is Always Tired?

I am a little worried about my 8 yr. old chihuahua. He has been sick lately. He has HGE (Hemorrhagic Gastroenteritis). He has had it for about a month now but is getting over it. He breaths heavily while he sleeps but he runs around fine during the day.

His sleeping patterns have changed. He use to sleep half the day now he sleeps whenever he can. Sometimes I pick him up and put him on his feet and he drops and goes back to sleep. Should I be worried? I am taking him to the vet but they cannot see him until next week. Any help would be appreciated. Thanks.

By michael from AUS, QLD