Why my orchid leaves are yellowing?

[KC Kam]

Greetings all,

I need some advice...

I have an cattleya orchid that was under my care for 2 years and has been blooming twice too. The 2nd time bloom was after i moved it to a new location..practically just 2 feet away. However, recently it leaves turn yellow. Orchid leaves usually turn yellow from the oldest bulb but in my case it is not. Not only it didnt drop leaves from oldest bulb but few pseudobulb leaves turn yellow and dropped.

Do you think is due to watering or some fungi / bacteria attack?

Please help to advice

Thanks.