It could be improper watering, it could also be lack of humidity, my leaves start to go brown when I bring her in for the winter, I don't immediately cut off the leaves since they are still giving nutrients to the plant. Are you giving her a lot of light? Whats your watering technique? Post a pic if you can.

Yes please post a pic. Sounds like lack of light and overwatering. Where are you located?? The pups will slow the mother plant down but wouldn't cause yellow leaves or browning.