If is simply from dry heat, try running a humidifier to make her feel better. However, she may have also picked up a cold.
A cat at her age should be able to fight off a cold on her own, however, keep a watchful eye on her. Lots of cats will stop eating if they can't smell which is very dangerous. If she stops eating for more than 2 days, she risks developing a liver problem called hepatic lipodosis. This makes her feel so bad that she does not want to eat, and the only cure for it is, well eating, and most cases need force feeding. She will need to go to the vet for antibiotics immediately if she stops eating, has a green or yellow discharge from her nose or eyes, becomes lethargic or her condition worsens in any other way. Bring her into the bathroom when you shower so she can breath in the steam to help clear her up and make her feel a little better. Really the most important thing is to keep an eye on her for any of the things mentioned above.
I hope she feels better real soon!