URI/Upper Respiratory Infection Raspy Breathing?

We just got a female guinea pig a week ago today. We havehad GP's in the past but not in the last 5 years or so. She came with a verydirty cage, (pine shavings), nothing in the cage - not even a food bowl. Shehad several open sores from scratching so much. She was immediately treated formites, and will get a second dose (Ivermectin) at the 10 day mark. Her soresare healing nicely, scabbing over and new hair growth. She is now receivinghay, and fresh veggies every day (she was not in previuos home), and I am now wondering if she is pregnant. Theysaid she had a companion that died but didn't say how long it had been. Hopefullyshe is just gaining weight nicely. My question is I can hear her breathe. She hasdone this since we got her, (so a week today) is a raspy sound. She is breathing at 50 beats perminute. I changed her bedding to paper bedding 3 or 4 days ago thinking maybeit was the pine. Sometimes you can barley detect it if at all, but when she gets excited or nervous is veryapparent. No runny nose, no crusty eyes, no coughing, etc. This is the only thing.She has a great appetite, gets excited at feeding time, is pop corning, etc. What could this be? Thanks in advance.