Orchids should not need much water this time of year, especially in a shaded position. Also, they will drop off a few old bulbs. If the whole plant is not affected, I wouldn't worry too much, but it it is, you might want to seek advice from your nursery or orchid club.

This could be a sign that there is a loss of roots. Now that the cooler weather is here you could place the orchid where it gets full morning sunshine. Make sure the bark mix you have it in is well drained. Only water when you dig into your mix and it is almost dried out. Most orchids die from too much watering before not enough. Hope this helps.