A long time before I was diagnosed with Crohn's Disease ,I ate venison a couple of times and it didn't bother my stomach. Last night ,I had some and I was on the toilet four or five times. Why did I have trouble tolerating it last night?
I think the answer is in your message- pre CD you were fine, and post CD you were not.
Something about the venison I should think does not agree with your system now you have Crohn's disease.
Also it sounds like something you eat rarely so that could be another factor.
I have had to give up many foods since becoming sick. Some I give up totally but others I try again with after a little while when my confidence is back. Then I find out whether I can (or should) resume a favourite food and sometime's I can't.
In addition occasionally I can successfully build up a tolerance to something which bothered me in a large dose.
I think StarGirrrrl hit the nail on the head. If you haven't had it since you developed CD, then it probably is the CD. Also, if you're having symptoms now, that could be the cause.