Are you seeing any benefit at all from Humira? They say that sometimes Humira can take a while to start working. I'm sure other people on the board will chime in and tell you how long it can take Humira to work. I've heard people also say that Humira and Remicade are very similar, and so if Remicade stops working for you, then, it's likely that Humira won't work for you either. The other anti-TNF agent that has been approved for Crohn's, is Cimzia, and lots of people here claim success with it. So, that's probably what's next in terms of meds. If that fails, I believe there is another biologic called Tysabri (originally developed for multiple sclerosis), but it was associated with 2 rare cases of PML, and so is only used I think if patients fail all other therapies.
Other than that, the only thing I can think of is perhaps some diet modifications (which I'm sure you've already been doing, given that you've had crohn's for 19 years), perhaps giving the SCD a shot. Also, probiotics if you aren't taking them already can probably help (SCD yogurt, + VSL3 maybe).
I hope you'll find relief soon. Hang in there.
Husband with Crohn's
Diagnosed March 2003 Ulcerative Proctitis
Diagnosed March 2008 Crohn's & C-diff, hospitalized 45 days
Canasa, Lialda, Remicade, VSL#3, Florastor
In Remission since June 2008
Stopped vancomycin for c-diff Jan 1 2009
C-diff free, until Sep 2, 2009
Fighting c-diff, I guess for life