Sum of Last Five Cells that have a value

So I have a sheet that contains the type and number of fish caught on specific dates

column A contains every day
column B contains the number of bass caught that day (if any, could blank)
column C contains the number of blue gill caught that day (if any, could be blank)

I would like column D to be the number of bass caught in the previous 5 days where bass were caught

So i basically need a formula that sums of the last five cells that have a value in them.
Ideally if there were not 5 cells that had values in it (like at the beginning of a month) I would like it to read n/a but that really isnt a big deal

If anyone could help me I would greatly appreciate it.

THanks for the reply. I for some reason am getting an error. I attached the file to this. Could you please take a look at it and tell me what I have done wrong?

Also this is just an example. My actual spreadsheet will contain over 2,500 rows. Do I need to update the formula to reflect this?

Originally Posted by Tony Valko

Try this...

This array formula** entered in D2:

=IFERROR(SUM(B20:INDEX(B2:B20,LARGE(IF(B2:B20<>"",ROW(B2:B20)-ROW(B2)+1),5))),"N/A")

Update: I was able to fix it and i am no longer receiving errors but for some reason that values that are being returned make no sense. I attached my updated example file. I also slightly miss spoke. I would like column D to be the number of bass caught in the previous 5 trips not including the "current' one. If you look at my attached example to this post I included a column of what the formula should return

Yep that worked! thank you very much.