I don't usually question a doctor's diagnosis but I'm not convinced you do have Crohn's. I think you could just have UC with a caecal patch. More information on it in this thread.
/www.healingwell.com/community/default.aspx?f=38&m=1557255If you had a colonoscopy, presumably biopsies were taken. Biopsies usually confirm whether it's Crohn's or UC. Admittedly there are some cases where the biopsies are non-specific or ambiguous and so a definite diagnosis can't be given. But I'm wondering what your biopsies showed.
I'm annoyed at your doctor for telling you to stop all medication. You should have stayed on Lialda at least, if not the enemas.
Humira (and possibly methotrexate? You mentioned another type of injection) does seem overkill, unless the inflammation was severe. In which case it's reasonable to put you on a biologic. But since enemas worked so well before, I'm not sure what your doctor's reasoning is for not giving the enemas another go.
It can be normal for Crohn's to present mildly, yes. Sometimes because it really
is a mild case; at other times because it hasn't had long enough to develop into something worse. I don't know which category you fall into.
I'm glad you're getting a second opinion. If the second doctor confirms Crohn's, then I'd be inclined to accept the diagnosis. (Apologies if this reply is all over the place. I'm severely sleep deprived :-/)