No need really to lower humidity for a mild RI. If she has A LOT of congestion, you wouldn't want high humidity breaking that up. Raised temps to high 80s 24/7 (NO NIGHT DROP) will keep her natural immune system at optimal performance and she should be able to shake it on her own. If she gets worse or doesn't improve in a week, then she might need some Amikacin or Baytril to kick it but usually just the raised temps do the job if you catch it early.
And then of course, she may not be sick at all and just has an oncoming shed with loose skin in the nostrils. Gently squeeze her lips together and see if any bubbles come out her nostrils. Open her mouth and look for excess mucous. If you don't see anything coming out of the nose or mouth, she's probably just joshing ya
