What to do when one is stuck in a plateau?

I've lost 26lbs but I've stayed at the same weight (159 lbs) for about a week and a half now. Im worried bc i've changed my exercise routine (i've added strength training and have switched my cardio to zumba). I talked to my nutritionist and she has switched my nutritional intake (upped a bit of carbs and fat in CERTAIN meals). So what could one do when one has hit a plateau?