Is this a disease caused by a lack of calcium and magnesium?

Your leaves are really dark green which definitely says you have excess nutrients. Not sure what you are feeding or if you are in soil but in soil you want to feed every third watering. Water, water, feed, repeat. Most plants usually don't ever need more than half the manufacturers recommended dose unless they are growing really fast. Less is more when it comes to nutrients so easy does it. I would give it plain pH adjusted water on the next couple waterings and let her use up some of those nutrients . Also water until you get a good amount of runoff to help wash out excess salt and nutrients. Good luck!