Thank you for this information.
I appreciate he may have been eating grass, but a noticeable reduction in appetite is always a concern.
As a rule of thumb, not ingesting any food for 4 hours or more is a red flag and deemed an emergency.
We are so cautious about this in bunnies as they are prone to a condition called 'gut stasis' when not eating, which means the gut fills with gas and water/food and bloats up, causing potential death.
I would advise an emergency vet check to assess Sky and determine why he has stopped eating. There will always be a reason and it may be e.g. overgrown teeth, a bladder infection etc. We need to address this.
We also need to prevent gut stasis from setting in, which usually means providing fluids, syringe feeding a liquid diet and providing e.g. pain relief and gut stimulant medicine.
If at all possible, I would be going to the nearest emergency vet right away.
Please ignore any phone call requests as the website sends these automatically, I am happy to talk via typing.