Hi this too happened to me.I was told it was 'shock', have you only just brought the plant or have you had it awhile?.
After this happened to me all of the plants were put into 'sick bay', I nurtuered them with a product we have here in Australia called 'seasol',do you have this product in america?,it is based on 'seaweed extract' and helps to rejuvinate the roots, it puts,lot's of 'good bacteria' back into the soil.
The plant should be just 'moist', and only put into a pot apx 2inches larger than needed,if it is in to large a pot this can cause the 'soil' to sour and turn 'rancid'.
If the 'roots' are brown and no 'white roots then it's probably 'root rot'.try repotting into some fresh soil, for acid loving plants, and give them a 'sesol' tonic, I did this with mine and now they are growing nicely, hope this helps, have a nice day ,cheryl perth australia.