How to find each unique rise and fall of a 'square wave' like data

Hi all, I am trying to get the individual chunks of data that span from the first drop to the next rise. I would like to analyze each chunk to do curve fit, and plot separately. I was hoping to iterate through them in a for loop and hoping to find a way to find the index of those points. 

Any ideas? I have looked at Extract and FindLevels but not sure how to use the results of those operations as input to the loop.

Thanks