Last Occupied Cell To The Left And Equal To Or Above Current Cell

I've been pounding away at a project for two days trying to determine a way to identify a solution, to no avail.

Here is some experimental code. Under the assumption that in Column "A", every fifth line contains some text (a, b, c, etc) I want to place a function in column B that would identify the closest occupied cell above and to the left of the cell containing the function. The sub achieves this, but the function has a problem because of the Activecell line. Is there a way to identify the location of the cell containing the function to act as a reference point for the range?

Sub find_last_heading()
Application.ScreenUpdating = False
x = ActiveCell.Address
ActiveCell.Offset(0, -1).Select
last_heading = ActiveCell.Text
Do Until last_heading ""
ActiveCell.Offset(-1, 0).Select
last_heading = ActiveCell.Text
Loop
MsgBox last_heading
Range(x).Select
End Sub
Function cathead(Optional reference)

Dim cell