I think that tools like this are great, but there already are some in this space (e.g., mySymptoms [1]). How will you differentiate yourself?
There are many more mood trackers than apps that allow you to track one dimension such as mood and not both symptoms and potential contributing factors, but as you point out there are some apps doing this already. Existing apps that track both symptoms and mood have two challenges:
1. Staying motivated to continue to log data daily as a patient goes through an evaluation is difficult if record keeping is done with pencil+paper or an app.
2. Apps that track more than mood have a more complicated UX to handle input across a variety of dimensions.
Apps like mySymptoms do make self-evaluation and data collection easier because the patient will usually have their phone with them; but this is still a chore. mySymptoms was designed to track symptoms for Irritable Bowel Syndrome and the UX reflects the motivation level of that user group.
Instead of a log keeping app, I want to make an app that will act like a personal lab assistant guiding the patient through their study of 1. Here is how I am trying to make this process of record keeping easier:[EDIT: fixed line breaks]
1. A UI/UX that allows data entry with as few touches as possible: each datapoint should be able to be entered with a single touch or gesture (voice interaction would be useful too, but one step at a time).
2. Present the user with one question from the lab assistant at a time instead of providing a daily grid to update.
3. Don't wait for user action, but prompt the user to interact with the app. Timing of prompts can be triggered by learned timing of user interaction with the app, desired medication/eating schedule, and sensor input to ask questions at the right time (some users my respond to prompts better while on the move while others when at home).
How to pursue this idea without charging patients is still a problem I am trying to solve. Here are two ideas I have:
1. If we are able to ethically collect anonymous data for use in research; institutions could pay a subscription for the data (This seems more suited to a non-profit company)
2. With the increase in use of mobile applications in patient care and research, this app could be put out for free as a promotional tool for a company that specializes in creating mobile software for medical research.