Sneezing Guinea Pig Sneezing?

I have two new 3 month old female guinea pigs. I just recently had one before the two new ones but she had a scab that could have been mites and my mom made me take her back because she can't deal with vet bills because we are running VERY VERY low on money. Anyways one of the three month olds seems to be sneezing more than the other. She usually only sneezes like 3 or 4 times after she eats hay (which is a lot haha!)and after she sneezes, she wipes her nose I'm not sure if they all do that but I am trying to give as much information. She eats and drinks normally, popcorn runs laps, and is very vocal(I've only had her for three days!) Also, the other one is very scared and rarely comes out to eat hay. I'm thinking it might be the hay? Also, the sneezing one lays in the hay rack and digs her face in the hay so could it be just the hay? I'm very worried and I really don't want to take her to the vet.