Certified GKH Gardening Expert
Watering on a schedule will not be proper for a plant. It will need water as it starts to dry down to about half an inch with these plants. This will be completely dependent on the conditions around the plant and how much it is respiring. This can change quite frequently.
It is also best to have this in a much lighter mix than you would a typical houseplant. Potting soil mixed with orchid or cactus mix is best. You could even mix cactus mix with small amount of compost. At the very least, potting soil should be amended with peat moss. This will help it to dry out a little faster, as the faster your plant can cycle water the faster, and better it grows. Keep this new mix slightly moist, allowing it to dry out only down to a half inch between waterings. They need to never dry out, but they can't sit in saturated soil, either. Allow all extra water to drain out of the container completely, and you will see a drastic turnaround.
You will also need to use a fungicide. Your photo did not come through, but what you describe sound like a fungal/bacterial infection. I'm wondering, too, if that container has drainage holes.
These articles will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm