Respiratory infection?

My oldest chicken, about 7 now, has been acting off lately. She hasn’t been eating much, probably not drinking much, and just separates herself. Last couple days I haven’t seen too much wrong with her, maybe a little nasal discharge but it’s also been colder out. Today, I went outside and walked up to her thinking I saw something on her beak. Upon picking her up I realized her breathing sounded almost crunchy and I rushed her inside. Then she started to vomit, which was brown and sorta foamy and there wasn’t a lot. Does this sound like a respiratory infection or something else? And is there anything I can do to heal her or at least make her more comfortable?