Noid Phal leaves with reddish patches on leaf edges

[sweta]

Hello Orchid Pals,

One of my phals has leaves that are turning reddish suddenly. I'm not sure of the cause. I repotted it about 3 months ago after it was done blooming. It was doing well initially for the most part but recently its been struggling, leaves turned floppy. I thought it was dehydration and have been watering regularly. But today I noticed the leaves with reddish coloration. Flowers are white with light brownish pink lip. Its potter in bark, fertilized every 1 week in summer and every 2 weeks in winter. House temperatures are 70F daytime and 65F nighttime. It sits on the window sill and outside night temperatures have been close to freezing. Humidity is about 30-40% inside the house..Please have a look at the pictures and let me know what would be the best course.of action.