The second thing I need to know is that if having Cystic Fibrosis and Crohn's disease would stop me from being a commercial/recreational pilot.
Welcome, and hopefully this helps:
https://www.faa.gov/other_visit/avi...signee_types/ame/fasmb/media/201003_color.pdf
That newsletter, directed at the FAA Airman Medical Examiners in 2010, says there are 113 people with CF who had Third Class medical certificates. The article discusses that the primary concern is lung function and usually the issuance of the medical is done on a special issuance renewed at shorter intervals than a regular medical for "under 40 years old".
It doesn't look to me like there's any mention of any CF patients qualifying for Second or First Class medicals.
That all said, it sounds like recreational aviation is maybe the best you can hope for, but you'd want to speak to an expert, that's just me reading the article.
On the recreational side of things, there's changes coming -- you may be able to have your own personal physician sign a form that says they believe you're safe to fly and that's that, but the rule changes are still unknown.
Also as some have mentioned, gliding and certain other aviation activities allow a person to "self certify" so to speak and don't require a medical certificate. However... and it's a big however... if you DID apply for a medical certificate and were denied, FAA considers that to mean they looked at your case and you have a condition incompatible with aviation and you can not self-certify after a denial.
So...
The long and the short of it is:
You can probably fly some, but unlikely to fly commercially. (That last part is a guess.)
You may want to be extremely cautious about how you go about applying for a medical certificate if you need one for the sort of flying you want to do, and you should seek specialized assistance from a Doctor who knows the process. Many here recommend Dr. Bruce Chien. AeromedicalDoc.com is his website.
Above all, CF affects your lungs and flying could run risks to your health that you should study and understand with assistance from professionals. Your health is more important than any of the above. Health first, flying second.
That's just the CF part. I can't speak to the Crohn's.
I think even if you planned to stick to areas of flying where you self-certify medically, I would want you to have spent some considerable time researching the effects of the CF and how it relates to aviation, and talk to both your own medical professionals and someone fully versed in the FAA medical process like Doc Bruce at length before flying to make sure you aren't injuring yourself.
But as of 2010 from that article, 113 people have done it.
This post should NOT be considered medical advice. This one sounds like it's square in the "You need to talk to professionals." category. But it doesn't sound impossible, depending on your specifics.
That's what I would tell you if you came to me and wanted to start flight training... especially after reading the warnings about hypoxia in that article. I'd want to make sure flying wasn't going to harm you or others, and I'm not qualified to make that determination.