Guinea pig is sick ! heeelp!?

okay so i just adopted a guinea pig from a pet shelter and the foster lady person said they were healthy and after two weeks one of my guinea pigs is sick she barely moves she wont eat or drink and she has boogers and eye crust and diarrhea. and i cant take her to a vet because my mom is on a buissness trip and grandma cant drive . what can i do to make her feel a little better or something ? thanks