my 4-5 month old guinea pig got sick about 2 weeks ago. He was sneezing more than usual and sniffling when he breathed. At first I didn't realize how serious this could be and then spent a few days trying to locate a vet for him in the area, most wouldn't see him. Finally he was seen and the vet said the infection wasn't in his lungs and prescribed tetracycline since he is so young for 10 days. He finished that yesterday but is sneezing and sniffling again! His appetite is normal, and he's as active as ever, but I can hear him breathing across the room. He has fleece bedding and I clean the cage regularly. He has plenty of vitamin c. Any suggestions?