Nothing

You were still coughing when the mist cleared but that was the worst that happened to you. The rouge meanwhile had passed out. Was that some sort of knockout attack? That would explain why the human was **** despite the fact that she hadn’t seemed to have taken any more damage but why were you awake? Had you picked up some sort of resistance when you’d leveled? Only one way to find out and there was no immediate threat even if you were sitting in the middle of a straight hall.

Giant Rat
Lvl: 2->10
Melee Attack: 3->14
Ranged Attack: 0->1
Special Abilities:
Diseased - 5% chance that a melee attack will deal poison damage.
New Abilities:
Toxin Immunity - Ignore all non-magical toxins.
Continued...

Yes! Eight levels. Though why did you get a ranged attack value, you didn’t have any ranged attacks. No focus on the positive; you were now immune to non-magical toxins, which was a bit hair split-y but still that clearly covered the whatever the rogue had planned to use on you. Not just that but there was also a second page to your level-up screen. Whatever could that mean?

Growth Path:
Rat King - Command lesser rodents.
or
Ratling - Use tools like a human.

Looks like you had a choice to make. Or did you? Had you hit some sort level cap for giant rats? If you didn’t choose would you never grow again? Why couldn’t you get more information?