Show last 3 chances

Given the need for each value to also be unique I think a native function will prove expensive (& ugly) ... are you open to a UDF ? (ie VBA Custom Function)

Not very elegant but perhaps along the lines of:

Function Last3Unique(rngHdrs As Range, rngVals As Range, rngPrec As Range) As Variant
Dim vResults(), lngRow As Long, lngCol As Long
vResults = Evaluate("IF(ROW(" & rngVals.Address & "),REPT(" & rngHdrs.Address & "," & rngVals.Address & "))")
For lngRow = UBound(vResults, 1) To 1 Step -1
    For lngCol = UBound(vResults, 2) To 1 Step -1
        If vResults(lngRow,lngCol) <> "" And Application.CountIf(rngPrec, vResults(lngRow, lngCol)) = 0 Then
            Last3Unique = vResults(lngRow, lngCol)
            If IsNumeric(Last3Unique) Then Last3Unique = Val(Last3Unique)
            Exit Function
        End If
    Next lngCol
Next lngRow
End Function

Above stored in a Standard Module and called from cells per

K5: =LAST3UNIQUE($A$1:$F$1,$A$2:$F5,$J5:J5)
copied down and across - eg I was using replica matrix K5:M33

Whre first parameter specifies headers, second values to be used up to that point, third specifies preceding results

NOTE: the above requires you have a blank column to left of first result column - ie J is blank
(this is to validate that current result is unique for the row)

You should find that you can alter the headers etc and the UDF would reflect immediately.