Oh no! You took her back?! Did they give you your money back? If not then please go immediatly and take the
GP back, do not sign anything that absolves them of any liability. It is unlikely that they will treat her properly, if at all. Normally petshops put a sick animal in a back room to take it's chances all by itself. Take her to a good exotic vet and submit your bills to Petco.
Petstores are well known for selling sick or pregnant animals that often don't survive or need extensive treatment Here is a thread to read up on some horror stories.
http://www.guineapigcages.com/forum/...r-threads.html
The green crusties most likely aren't an eye infection. It's an URI. Mites are on all animals and lie dorment until stress or weakness allowes them to take hold.
Here is another thread from a couple of days ago with a person having the same problem. You may learn more there
http://www.guineapigcages.com/forum/...ffy-noses.html
In the future please, please, please do not buy from petshops. Nothing at all. No food, no animals, no bedding, nothing. We can help you find MUCH better food and supplies then the petshops carry as they are known to carry poor quality foods that are geared to make the humans buy them because of pretty packaging, boastful claims and pretty colored bits that look like treats.They are animal abusers that cause HUGE problems for animals that most consumers do not see. There are rescues everywhere with
GPs and other animals begging for a new chance at life. We can help you find these animals.