... and a gentle question which may help you decide...
Piggies shouldn't be kept as solitary animals because unlike feisty, fighty hamsters they get so very lonely. Pet shops in the UK don't usually sell single pigs for just this reason. Breeders shouldn't either. In some countries it's illegal to keep a lone guinea pig. A companion piggy hasn't been mentioned so far...
If she has a companion are they sneezing and nose-running too? This can help you decide if it's environmental or a URI. If she is alone we would have to advise getting that vet check so she has the all-clear (they will listen to the lungs in a way we just can't do) and also check her over for any other issues like mites/lice or toothy things. Then she (double-check the sex!) can find a companion and happiness
Pigs can die of chest infections even if they can fight off the infection. You might already know all this but I'll put it again in case this thread comes up for anyone else doing a search. When they are ill or in pain they eat less - and sometimes they stop eating for a while. Depending on the piggie, age, condition, time etc. this can cause 'gut stasis' where the gut slows down and then stops working altogether. This is a piggie thing - quite different to people, cats or dogs. They might recover from the chest problem but never eat again and will die. Keep an eye on her weight if you suspect illness - daily weighing (with a bit of up and down) shouldn't show dropping weight all the time. Make sure she is still munching her hay. A few pigs can have allergies but that's why a vet trip is recommended - we can't tell over the internet! This might all just be a storm in a teacup but we have to warn of the worst case scenario so people don't get caught out.
If this whole thing is freaking you out and you are thinking maybe getting a guinea pig was a mistake please don't just pass her on to an unknown home via social media - surrender her to a decent rescue (there is a list on the green bar above) who will get her vet checked, pair her up, and find her a secure future. Rescues are a great source of healthy piggies because they love them so!
Good luck with whatever you decide - we know you love her because you're posting on here in the first place for her sake
