Kara -
I have been a legal assistant working for labor/employment defense attorneys for 8 years so I have some background with this kind of thing. First, as others have posted, we need a little more detail as to what happened. You say that you were doing something that everyone else in the office was doing . . . did you do something that violated a company policy? If so, then they had every right to terminate you for it despite the fact that others are/were doing it too. How long were you employed there? And did you have any prior discipline or performance issues?
It is true that you can contact the EEOC and file a complaint there. If they feel there is reason to investigate, they will. If your case there is dismissed, you can then proceed with a civil action in court. Be prepared to wait a long time to litigate if it gets to that point. We have cases that still have not gone to trial where the employee was terminated as much as 5 years ago. Truthfully, most cases don't even make it to trial.
You have to decide if it is really worth it to you to pursue this. If you honestly feel you were terminated due to having CF, by all means, contact the attorney others have referenced and see what she thinks. It is not as easy to win large settlements from companies as people think. There is a lot to go through to get to that point and, most importantly, there has to be merit to the claims being made.
Good luck and post again with more details if you can.