Sneezing Guinea pig very allergic to carpet?

I have my guinea pig in my bedroom,I have carpet in there that is 6-7 yrs old,it will be getting replaced with hardwood floors next week..I had my guinea pig out running around in my room for half an hour,I picked her up,she was lightly sneezing and clear almost like water,stuff was coming out of her nose..she's sneezed before when I had her out on the carpet before..she sounds stuffy,she eats all of her greens,her pellets and drinks well..I keep her cage very clean,every 2-3 days I change out her fleece(free & clear detergent),she made it to 1 lb 13oz,last week she was 4.30 oz..so not losing weight any weight. Any ideas on what else it could be?? She had URI last month,other than her sneezing from running around on the carpet,she doesn't sneeze in her cage like she did when on the carpet.

She's about 5 months