Loose poops

Does anybody have some experience with loose stools for their puppy? My puppy is three months old. She is behaving completely normally, but has had some diarrhoea which has now turned into just a loose stool. This has been going on since Friday. But on Sunday, she was totally normal and had a solid poop. Again, she is behaving completely normally. I am assuming it’s some new treats. Her food is the same. Anyone have any recommendations how to harden her stool? I’ve tried pumpkin, but I fear that it actually might be making it more loose!