Is my guinea pig in danger? [Urgent]

Question
I recently purchased a guinea pig from PetSmart. When I got him he had a small scab on his ear and the employee at the store insured me it was nothing. The first day after I brought him home he did not eat, however her has started eating a lot and his fecal matter seems to be normal. He is sneezing a lot. What I thought to be normal eye crusties like humans have seems like it could be eye discharge that has dried up. He is also having nasal discharge I believe. I am worried that he has pneumonia. I have heard that it is very deadly. I would like to know what the signs are as to whether or not he is getting better. He seems to be eating a lot, I have read in some  cases they will lose their appetite and he has not. I have only had my guinea pig for three days now and I have no clue as to where to go for a vet. I think time might be of the essence so if you could please respond quickly that would be much appreciated.

Answer
Right now he most likely has an Upper Respiratory Infection, which could eventually turn into pneumonia. The scab on the ear is from another pig biting it, but I have heard so many problems with pigs from petsmart now. I have a lot of information on my website for the cure to URI's, his case is not too severe right now, so he should need antibiotics from a vet unless he stops eating or gets worse. All of the dosing is on my website, keep him on Robutussin DM, Vicks Vapor Rub, and the other supportive care for at least 3 days, if you do not see improvement he will need antibiotics. My website is http://woopets.bravehost.com . It is under guinea pig information, then listed in Upper Respiratory Infections.
Brittany