Oh no!!
Poor Archie...Did you call your vet to see what advise they had too? It sounds like you did all great things by keeping him warm, nutrical and everything, oh bless your heart you must be so worried.
Maybe Archie has had enough snow play for awhile and tell him spring will be here soon!! Plenty of sunshine and warmth for him to bask in.
Keep us posted on his condition and hugs to Archie!!