What is that soil (under the bark chips)? My initial impression is an over watering situation.

It is cactus soil

Is it a Rhipsalis (Epiphyllum)? They don't like being damp for long. What more can you tell us about this little guy? The clay pot has a drain hole, yes? What kind of light do you keep it in?

What is the mix the plants potted in? It looks like it holds water. I would have it in something extra gritty like a 60/40 mix of perlite/pumice and cactus&succulent soil.

How often are you watering? These go dormant during summer so I wouldn't water too often.

Does the pot have a drainage hole? These like a fast draining soil and proper ventilation. So hopefully there is a drainage hole.

Where do you live? What kind of light is it getting?

I don't know what kind of succulent it is. It is in Black Gold Cactus Mix and is very fast drying. The pot has a hole in the bottom. I have a plant light strip around it with red and blue lights and it is also there is a big window in the room but not right by it. I live in Nebraska but this plant stays inside all the time.