Yeah, I agree with Laura...you should just try to be really assertive with your clinic and insist that you need to be seen NOW. Honestly, I've rarely heard of a CF clinic that would make you wait almost a month when your symptoms are that severe. I mean, it's not like you have a splinter!! If being assertive doesn't work, be aggressive.
Also, I'm not sure exactly who you've talked to when you tried to get an appointment. If you haven't yet, try to talk to the nurse coordinator for the CF center/clinic. Usually they can pull strings and fit you in when the regular appointment scheduling people have no idea how crucial it is. When I'm sick, I call my nurse directly and she always says, come in - we'll fit you in. No questions asked.
If that doesn't work, try to speak to the social worker. If that doesn't work, try to speak to the doctor directly or even call the hospital and ask for the pulmonary doctor on-call. Then tell them you know your body and you are NOT well and need to be seen immediately. Good Luck!!