Insert a signal into an existing Metatrader 5 indicator.

Insert a signal into an existing Metatrader 5 indicator. The indicator in question draws candles in two different colors. I need a signal, if in the last period a candle appeared and in the immediately following period a candle different color is displayed.  The signal should be displayed acoustically as a pop up with the relevant currency pair as well as with arrows in the chart.