The GetCurrentField() function is not supported in Qliksense. But there is a workaround to achieve this using the below expression.
I have created a drill down group with Year, Quarter and Month fields. Use the below expression to dynamically get the current active field,
if(GetSelectedCount(Year)=1 or Count(DISTINCT Year)=1, 'Quarter',
if(GetSelectedCount(Quarter)=1 or Count(DISTINCT Quarter)=1, 'Month',
Try using a cyclical approach if changing the context of your chart is important. In this example I used a extension called qsvariable to use the same space to present the measure in different context.
Drill down doesn't and in my opinion should have a better way of presenting labels at the moment.