couldn't have been a huntsman
those symptoms sound too severe - a hunstman bite swells and is (I'm told) painful, but not dangerous.
By the sound of it I'd say it could have been a redback spider, they're small, and so aren't so easily detected, particularly since they usually hide in nooks and crannies (like in sheds and garages). Plus, his symptoms sound like that of an untreated redback bite.
Luckily he made it .. the treatment is readily available here but obviously not so well konwn in the US.