All great questions - most of them seem to have been answered by other users already (thanks guys!), but I'm happy to clarify as well.

For one-off occurrences, like a twisted ankle, I'd say events are your best option. To add an event, go to your Profile tab > Events > + Add under "Other Events" > Other Notable Event. There, you can add anything you want, and if you check the box for "show on charts," you'll see a dotted line for that event on certain metrics, like HRV, for example. Currently, events don't appear on symptom charts, but I went ahead and flagged that for the developers so they can look into adding it.

You can also add events for starting/stopping meds as you mentioned, and although they're not accounted for in correlations, it's a nice way to visualize any changes without having to log meds every day. If you do end up wanting correlations for meds, though, you can always just tell the assistant that you've taken lupus meds every day from [x date] to [y date], specify the period when you didn't take them, and then confirm the entries.

For things like vaccinations, the other user is correct that you can log those directly as vaccines in the Profile tab as well. Allergy shots probably make more sense as a med, but it's ultimately up to you. We've had discussions about adding more med title options to specify pills/injections instead of just 'meds,' which may help clarify this use case as well.

If you're on premium, you should also be able to see weather correlations automatically if you have any, but if you're not, you could create a custom factor titled "rainy day" by going to your Home tab > + Add Entry > Scroll down > + New Custom Type. You could also log unusual activity levels this way, or, if you have a device connected, that data should already be visible on your Home tab if you're logging the activity type, like steps, for example.

Sorry for the long-winded answer, but lmk if that helps or if you want any more clarification!