Health app not is working in my phone after iOS 16.3.1 so what’s happened?

Many users who have updated to iOS 16 and above must have a similar issue if the issues stated by you are due to the iOS.

Unless you state what the issue is many in this forum may not be able to respond positively to the issue you are facing. 

With the limited information that you have provided, It is hard to even guess the problems faced by you. 

You may get faster and better responses to your query by --> Writing an effective Apple Support Commun… - Apple ...

Please re-post with detail so that someone else can help.

I have the exact same problem. All my health app data is gone after the update. The app crashes every time I try to use it. I don’t get my medication reminders. And the apple watch app is also not working. It’s not showing my activity on my iPhone but it is working on my watch. I can not use the watch app too, it is also crashing. Both iPhone and watch are up to date on software updates.

"Not working" is a very broad term. What exactly is happening?