I would watch her today, but in the meantime, give her a gentle tummy massage. If it’s a little gas, it should help to pass it. You don’t have to pick her up, just give her long pets and work your way down and all over her body so she likes it, but particularly under her belly area. Make it pleasant for her.
If she passes gas you’ll either smell it or she’ll head for the litter pan again.
Next thing to try is to get a little box of baby simethicone. She can have a couple of drops (don’t get a brand that adds anything like flavoring, etc.). Then stock up her hay and don’t give her more treats. You want her to eat the hay a lot to pass whatever might be bothering her. since she’s pooped, it doesn’t sound as serious, but it may be leading up to something worse without attention. Be sure to give her extra water also. Cut back on any treats – fruits, snacks, even greens in the broccoli family like kale, until she appears normal again. If worse tomorrow, call your vet in the morning. (Do you have any critical care in the house for her? If so, you can give her a CC treat ball to munch on instead of a regular treat.)