You've had the plant for 2 years? Have you recently moved it to a different location in your house? Changed the watering schedule? Anything?
I don't grow Desert Rose, myself, but there is an older thread here by a member who has a lot of experience with them. Perhaps there will be something there that will be of help to you. If not, one of our other members who grow this plant will probably drop by soon.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams