Soft poops can be a sign of a tummy upset.
Please stop giving all fresh veg and feed only hay and the normal one tablespoon of pellets to allow the digestive system to settle. Once poops normalise, which may take a few days, wait a further 24 hours and then reintroduce veg slowly so as to not cause a further upset.
If things don’t settle after a couple of days without veg, then please see a vet
It can be a good idea to give a probiotic to a piggy who is suffering from a digestive upset
Digestive Disorders: Diarrhea - Bloat - GI Stasis (No Gut Movement) And Not Eating
Probiotics, Recovery Foods And Vitamin C: Overview With Product Links