Are the hard pieces very hard? It is sounding more like constipation than obstruction to me. I have had bouts of severe constipation with my Crohn's, where I couldn't pass anything for several days. Eventually when I did go, I would pass hard, impacted faeces followed by liquid stool - this liquid stool can sometimes seep past the impacted stool in the colon or rectum, and is known as 'overflow diarrhoea' - I thought you'd want to know ;p
Glycerin suppositories worked great for me. Just make sure you have the next hour free and are close to a bathroom.
If you do develop severe abdominal pain, then go to the ER like scifigal said. I wouldn't worry about
the Remicade causing strictures: it's possible, but I think that theory has been largely been debunked now.
*googles* Er, maybe not as debunked as I thought: www.medscape.com/viewarticle/729747
From personal experience, I did seem more prone to developing obstructions after starting Remicade. I had a recognised stricture, but it was mainly inflammatory and would disappear if I went on steroids. So I dunno how much the Remicade had to do with it really.