A shock to the system

Explanation:
It means the talker are experiencing a sudden and unpleasant change.
Example:

1. My daughter has found starting secondary school a real shock to the system.
2. After such a long and hot summer, this cold weather has come as a shock to the system.
3. My first day back at work and it's been a shock to the system.

Diary:
Happy dragon boat Festival!
This weekend my friends came to visit me, so we had dinner together and long talks. The covid-19 is restarting in our country and I'm afraid I won't be able to Wenzhou for my work. At first sight, I was shocked and a little worried and then I made the adjustment and took all the result and see what I can do more.