The only Pokémon that have their Hidden Abilities available are the ones specified in the Pokédex spreadsheet, given because they only have one standard Ability and in most cases that Ability is kinda lame for the most part. Other species don't have Hidden Abilities (especially since none of the new Pokémon have them; I deliberately left them out of the designs).

For reference, the species with their Hidden Abilities available are Chikorita, Torchic, Oshawott, Pikachu, Swablu, Turtwig, Cyndaquil, and Froakie.

Also, hospitals suck. Hope you're out of there soon. =/

[b]Edit:[/b] The species mentioned above have an even split between their standard and hidden abilities, so they appear at equal rates.