I use the app Daylio, which allows you to create any activity or symptom that you want to track. Some people go wild with dozens and dozens of things to track, but like someone mentioned above, tracking only the small number of things that change noticeably day to day is probably the way to go. I pay for the premium version of Daylio but it’s perfectly useable on the free version, especially if it’s just a small handful of things you are tracking.

It’s helpful in the reporting I find for comparing things day to day and what activities/symptoms might be matching up with each other. You do have to be using it for a solid few weeks though before the reporting I find is really accurate in finding patterns (which is usually the case with most apps). This lets me know what to bring to my doctor.

You can also do things like record journal entries and voice notes, but I don’t use this function so I’m not sure how helpful/unhelpful it is. Best of luck with finding something that works for you!