Cat is female, usually uses her litter tray 2-4 times a day. Yesterday she had done a couple of small wees in it, plus probably went when outside.
I’ve kept her in today so I can monitor, I use clumping litter, there was one clump this morning, and one fairly large one this evening. She is pooing fine.
Eating ok, and drinking usual amounts. I don’t think she’s stressed, running around as normal, had a mad half hour on the stairs tonight 
She let me stroke her tummy, I had a little feel around, she doesn’t seem to be tender.
Any advice please? Thank you!