DAX SUM of last 3 months excluded current month for selected time period by slicer

[JFTvK]

Hello how do I calculate the SUM of the last 3 months excluded current month for selected time period by slicer?
The problem is that if I change the slicer, it does not show the last 3 months of the selected range. It shows only last 3 months from the perspective today. I tried to replace today but nothing I tried worked. 
I already have this: 

Last 3 Months =

CALCULATE(

    SUMX(Transaktion,

        IF(DATEDIFF(Transaktion[Transaktionsdatum],TODAY(),MONTH) <= 3

        && DATEDIFF(Transaktion[Transaktionsdatum],TODAY(),MONTH) >= 1,

        Transaktion[Umsatz],0)

        )

)

// Transaktion[Transaktionsdatum] is the table for the time

Thank you very much!

[JFTvK]

It worked perfectly fine, thank you so much! 🙂

[amitchandak · Accepted solution]

@JFTvK , Try measure like

Rolling 3= CALCULATE(sum(Sales[Sales Amount]),DATESINPERIOD('Date'[Date],eomonth(MAX('Date'[Date]),-1) ,-3,MONTH))

rolling 3 =
var _max =eomonth( if(isfiltered('Date'),MAX( 'Date'[Date]) , today()),-1)
var _min = eomonth(_max,-3) +1
BLANK())
return
CALCULATE([net] ,DATESBETWEEN('Date'[Date],_min,_max))

but if you want to display a trend then slicer need to be on an independent table

//Date1 is an independent Date table, Date is joined with Table
new measure =
var _max = maxx(allselected(Date1),Date1[Date])
var _min = eomonth(_max, -3) +1
return
calculate( sum(Table[Value]), filter('Date', 'Date'[Date] >=_min && 'Date'[Date] <=_max))

Rolling Months Formula: https://youtu.be/GS5O4G81fww

Power BI Window function Rolling, Cumulative/Running Total, WTD, MTD, QTD, YTD, FYTD: https://youtu.be/nxc_IWl-tTc

Need of an Independent Date Table:https://www.youtube.com/watch?v=44fGGmg9fHI