First off ditch the Miracle Grow. It's like feeding a diabetic candy. Use a more balanced fertilizer. Better yet don't feed at all right now, let your plant have a rest. I would give the soil a good flush to get the excess salts out of the soil. It does not need to be fed during the winter. I would say you're over watering. Look at my thread on keeping plants healthy through winter. It might help.

Thanks for the reply! Okay, less frequent watering, flush the soil, no fertilizing during winter (does it know it's winter if it's in an office with no windows and very little temperature fluctuation?), when I start fertilizing again use a balanced one--would Bonide 10-10-10 be better? And I'll go find your thread. Thanks so much.

Theoretically they shouldn't know the difference if the light and temps are the same, but they do. Plants are fickle creatures.

Thank you.