Hi Chris,
I don't know of any specific to CH but I know there have been some posts on here with folks attempting to create one and I think one other that had successfully created one. In the very beginning of my joy ride when being told I had migraine, I used an app called migraine buddy which was good for tracking dates, medications and pain scale but I soon got tired of it and switched to a self created excel log which I also tired of at some point in my journey. I guess I just felt like looking back at all the bangers made me depressed which I was already really good at doing especially when in a cycle which seemed to be the time I was most apt to visit the log. Anyhow, tracking can be a good thing especially if you are trying to gauge your next doomsday and get in front of it.. Lastly you can use the search bar at the top of each forum page and plug in key words like App and a bunch of past discussions will come up for you to review.