Tā zuìjìn xīnshìchóngchóng, bùzhī dào fāshēng le shénme.
She has been weighed down with worries lately; no one knows what happened.
Tips
usage
心事 means 'worry/concern on one's mind', and 重重 means 'heavy/layered'. Together they paint a picture of someone burdened by many anxieties. Often used to describe a person's visible demeanor.