Is this the start of the decline if Dad won't eat or drink?

Hi,
What am I supposed to do now? My Dad will be 97 next month and he is quickly declining I feel. He is still of sound mind and he takes no medication. He has led a very healthy life. However, all of a sudden there is something wrong with his stomach and he won't eat. He says it makes him sick and he pukes what he does eat up. Very little does he eat AND drink.
He was very dehydrated last night and I called 911 because he is so frail I can't physically take him to the ER. The ER sent him home and told him they really don't know what is wrong with him but yet they gave him three medications.

I'm not putting him in a home, and I know that's easier said than done, however, I can't do that. My Mother was in a nursing home.

I told him I don't know what to do and he said he did not know either. I think he just wants to be in his bed more than anything else obviousy. He is also just plain TIRED. Am I just supposed to watch him deteriorate? Is there any help at all? I am just looking for suggestions.

Thanks so much for reading.