Jack, when was your colonoscopy/endoscopy done? I was pretty sure I must have Crohn's as well. I had the tests run first time around 1999-2000. The symptoms came and went. It started to get really bad again in 2008 and the GI doctor didn't want to do the tests again, as if it was wasting his time. But with the frequent diarrhea, painful cramps, bloating plus constantly burping up bitter liquid I was persistent and they did the tests again. (sorry I feel gross typing this out) So this doctor could only come up with irritable bowel syndrome along with GERD.
He gave me various medications to combat both ailments. Trouble is, the medicine for acid-reflux made the IBS worse especially when he had me taking it twice a day. I was always sick and this GI doctor was losing his patience with me. Finally he just said, "We're running out of options here" and made me feel like an idiot. So I know how you feel when people don't take you seriously and you're always feeling unwell. You've got the right idea by stopping alcohol usage and if you smoke, quit because that can irritate your already sensitive intestinal tract too.
So what ended up happening with me is I was talking with a nurse practitioner at the shelter two years later. I gave him all the gory details and he explained that many times the two diseases go hand in hand. He advised me also that omeprazole, pantoprazole, lansoprazole, etc. are going to make diarrhea worse. Also when these drugs are overused, the more you find yourself needing them which makes sense. How come my doctor never told me this? (Just prescribed more pills like lomotil) It's not that these doctors are stupid but I feel some just don't care that much.
To sum it up, I believe the antibiotics you took definitely affected you badly. They are known to wreak havoc, especially with long-term use on your gastrointestinal tract. But you didn't give yourself Crohn's, it doesn't happen that way. It's an auto-immune disease and your doctor already ruled that out from all the tests. You didn't say how long it's been since you stopped taking those pills? You have to watch what you eat & drink. I really think you will be alright. It's easy to say stop worrying, but stress will make it worse. Give your body a chance to recover. It may take some time so be patient and take care of yourself!