Hi
Please take your piggy off any fresh food immediately. Hopefully, the poos will start firming up again within a day or two. You need to wait for 48 hours after the poos have fully normalised before you can start serving fresh food again. Start with some fresh herb and then add one more veg with every passing meal for the next three meals in order to not overtax the still tender microbiome.
Switch from weighing once weekly to weighing daily at the same time in the feeding cycle on your kitchen scales to monitor the food intake. Since at least three quarters of what your piggy should eat in a day is hay, you cannot measure it any other way to get an up to date feedback. It takes around a day in a normally moving gut for food to pass from one end to the other, so the poo output is always behind events. Step in with the appropriate level of feeding and watering support if needed.
Our digestive problems care guide and our medicating/feeding and weight monitoring guides contain all the practical and precise details on what to look out for, what to do and when to step in with more support, including what you can to in a pinch when you need to improvise.
You can also give probiotics and/or very freshly made 'poo soup' (i.e. live healthy guinea pig microbiome transfer) from a healthy piggy not on antibiotics to help stabilise the gut bacteria again. The recipe is in the syringe feeding guide.
Please take the time to read these links here, which you will find very helpful. They contain all the important information and practical how-to tips that we cannot repeat in full in every post but the guides will help you to navigate the weekend and the recovery.
Thankfully, as long as the poos are still having texture and are holding their shape, you are still dealing with a milder and not a severe diarrhea.
Digestive Disorders: Diarrhea - Bloat - GI Stasis (No Gut Movement) And Not Eating
Weight - Monitoring and Management
All About Syringe Feeding and Medicating Guinea Pigs with Videos and Pictures
In case there is a further deterioration over the weekend to fluid diarrhea, loss of appetite or bloating, please see a local vet. Your piggy may need extra subcutane fluid in the case of fluid diarrhea (risk of dehydration). This is something any general vet can do but here is our link with all the necessary information in case things go pear-shaped, especially with a weekend coming up and a big public holiday for the UK:
Emergency, Crisis and Bridging Care until a Vet Appointment
All the best.