Hi! Please take a deep breath and do not feed any apple.
If you have worries, please switch from weighing weekly to weighing daily at the same time. It is most likely just a little weather related blip and nothing to worry about. We've had a very hot weekend in the UK.
A lowered poo output can be just due to eating a bit less because of the weather (very hot and/or humid); keep in mind that it takes about 1-2 days to process the poos. If their is a gradual loss of weight over several days, then please see a vet once this goes over 50g and start offering additional syringe feed.
Don't offer more soft food, always offer extra fibre in support of the digestion; too much soft food can lead to fermentation and more problems. Hay makes over 80% of the daily food intake; fibre can even make safely up to 100% when a piggy is seriously ill and relies fully on syringe feed. You can't control that by eye, only by the scales.