It is probably a natural thing, not knowing how long it was in bloom before you got it probably has reached the end of it's bloom time.
I would remove the layer of moss from the top .
I assume the humidity is high where you are .
I would use a mix of finer bark with sponge rock in it .
If the mix is not breaking down just leave it alone , but watch for drying in the clay pot .
Also move it back to more light . Hope this helps a little .. Gin