I have a formula that is based on comparing the last value in a column.
Basically of not null it performs an action.

However I need the ones after that to be able to set up and find the last
different value e.g.

A
B
B
B

My formula so far is if Value<"" then do X
I even got it to say If Value<"" AND Value not equal to prior record.
Which would work for the second B

But what I really need it to say (to get to A) is
If Value <"" and Value IS Equal to Last Record step backwards until you
find the value of the first different record.

Is that possible?