Hmmm...when you say "pressure," is there any pain at all? Is it stiffness, spasmodic, constant, throbbing, intense? Could it just be physical; that is, were you hanging window blinds or squatting to change a tire? Are you on a new med?
I haven't read about something like this in my Crohn's travels, but I'll keep an eye out. Please post if it gets worse or goes away.