Thank you for waiting. Poppy is critically ill, and that is why I said a vet would be the best thing to do. It's incredible to me that vets in some parts of the country charge so much to see a pocket pet. Where I live, it would be about $50 to check her over. I'm going to give you several things to try, but first I want to mention that if Poppy has actually not eaten anything for several days, there will be nothing you or even a vet can do to help her. Loss of appetite in guinea pigs is extremely serious. It is called anorexia. If they go for a number of hours without eating, a condition called ketosis develops and the guinea pig cannot recover. Regardless, we will try.
First of all, you need to get rid of that pine bedding. Any cedar or pine is not a good bedding. I realize that pet stores recommend it because it keeps odors down, but it has been solidly linked to a number of health problems. Most of these health conditions don't show up right away, but take weeks to months to develop. The occur in all small mammals, including guinea pigs, rabbits, gerbils, hamsters, and rats and mice. Kidney failure, liver disease, and tumors are some of the possibilities. Animals kept on pine and cedar will seem fine for a length of time, but by the time these problems develop, it is usually too late to treat them.Guinea pigs that are particularly sensitive may develop skin irritations and fur loss, and respiratory problems. The following links will give you more details on the cedar and pine problems:
The best litters/beddings are paper-based ones, such as CareFresh.
Next, it is imperative that you get some food into Poppy. You will need to feed her from a syringe. You can make a slurry of crushed pellets, water, and pureed (baby food) vegetables. This can be more difficult than it sounds, so I'm giving you a link to a page that describes it in great detail, including variations on what to feed, and how often to feed:
There is a product called Oxbow Critical Care, available in pet stores, that would be even better than the homemade slurry, but if you can't find that, the homemade one is better than nothing. Be sure to put the syringe in the side of Poppy's mouth, not straight down her throat.
I'll give you this much right now, and will be back again in a few minutes with more.