Help!! I need advice

[vignoble]

Hi, I have 2 orchids. One has had its leaves turn yellow, then brown, then go limp and dark. Started a couple of months ago but I just cut the leaves off because I thought it was just normal. Now the same is happening to other leaves (see photos). I clean the leaves with a damp kitchen towel, feed about once a month and don't overwater (I let the roots soak and then remove the plant from the water and let them drain a while before putting back in to their pot.

This yellowing of leaves is now happening to it's neighbouring plant and I'm afraid I am going to lose both.

I'd love some advice on what might be wrong? What can I do? Plants are in the original "soil" they came in, never been repotted.

Thank you!

[stumac]

Looks like a fungal problem try fungicide