I've just realised that this question is actually an answer - you asked a question before about yellowing leaves on your Box, and I asked for more info. Sorry, didn't realise, but Margaret, it would have been better to add your response under the original question, or under my response anyway, as if you were answering it yourself, then I'd have seen it straightaway (we get notified every time something's added to a question we've responded to).
Anyway, you say its been in the same pot since you got it, but not how long you've had the plant - if it was more than 6 months to a year ago, chances are its potbound - turn it out of its pot to check, and then repot into fresh compost in a larger pot. Feed with Miracle Gro general purpose or similar a week later, and then wait and see what happens, keeping it well watered in the meantime.