Index Match Or Array Search Function

Here is the table I am working with

Date
Open
High
Low
Close
Volume
Adj Close
Semi-Annual Yield
Theoretical Bond Price
Index
Coupon
Total Value
Peaks
Troughs

[Code] ..........

The Relevant columns would be "Date" column A cell 1, "Total Value" column L cell 1, "Peaks" column M cell 1, and "Troughs" column N cell 1. What I basically want to do, in the next column, column O, is this: If cell N# = "Trough" find the previous M cell = "Peak" and take the L cell in that "Peak" row and subtract the L cell in the Trough row from it (like =(L4-L9)/L4)). Then in column P, if the percentage drop was 5% or greater, I want to find the days between the trough we are looking at, in cell n10, and the NEXT Peak, cell M11, using the corresponding dates in Column A.