Considered building something like this over a decade ago (because my mum has chronic health problems that are manageable but require a lot of management) and I'd recently been diagnosed with Chrohn's.

I thought about the design/approach that would work for her and her use case and my own and then I realised I'd be holding peoples most personal data (medical) and realised that I wasn't comfortable building a system that did that or that I could keep it genuinely secure, it simply wasn't a level of risk I was comfortable with and I've worked on/around payment systems etc but that is only money in the end (and the risk would be my employers).

For my personal use case I just have health.md in my `~/personal` dir, I put stuff in with a fixed structure, so I can grep it it later and that's about it.

It seems to work however managing a chronic in illness in the UK is going to be quite different to other countries, here other than tracking your symptoms and remembering appointments (and even then there is the excellent NHS app) etc it's a lot simpler.

I wish you good luck in finding something that does work for you and hopefully others, I've yet to see a system that works for even most chronically ill people.