For the code I am writing I monitor the changes in certain cell ranges to run functions and private subs. For this I use the Intersect function in the worksheet_change
It might be easier to "remember" the Range rather than the address of the range:
Dim Oldcell As Range
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Oldcell Is Nothing Then
Set Oldcell = Target
Exit Sub
End If
MsgBox "New cell is " & Target.Address & vbCrLf & "Old cell was " & Oldcell.Address
Set Oldcell = Target
End Sub