Brassia Verrucosa help

[hat trick]

Hi all,
I bought a brassia verrucosa in the fall of 08. The leaves are turning yellow and not just the older ones. I keep it outside here in San Jose CA until temps get below 38 and then I bring it inside for the night ( this has only happened a few times this winter.) I was feeding it everyweek and had it in full sun until about 1:30. For the past 2-3 weeks I have cut down the watering to every 2 weeks and the feeding to every 3 weeks still no improvement. Any suggestions would be appreciated.
thank you
Norm