If spots look wet at the border, quickly progress with a bad fragrant, it is sure a bacterial attack.

In the photo, you can suppose the bacterial progression seeing the dark wet area in the border of the spot of the leaf. If it is that, it is extremely contagious. If a drop touches the spot, it can contaminate other part of the leaves creating others spots.

You can save the orchids by several ways. I will not explain how here because, in function of the low of each country, some drugs are legal or not.