Potty regression help

Heather • Maggie’s mom

I need some help. My daughter (almost 3.5) has been potty trained for well over a year. Hardly ever has any accidents. Well, the last 4 days now she has wet herself. Not the full flood, she stops herself before it all comes out. But it’s enough that we need to change her pants. Why would this be happening? What should I do?