What's wrong with people who laugh and cry for a while?

It is an obvious abnormal behavior reflected after an emergency.

But if you are stuck in this mood for a long time, or if your sister has had mental problems herself,

Then be careful not to let stress disorder become a long-term disease. In that case, it will be difficult to recover.

Spend more time with her, talk to her about her illness when her mood is relatively calm, and don't hide it, which will make her feel uneasy and anxious and let her escape from reality.

Fear of illness stems from her life experience and reminds her of other terrible things, so spend more time with her, slowly accept the status quo, and face the status quo, her abnormality will disappear automatically.