Potty Training Trouble...

Potty training it going pretty fantastic and I'd say I'm a very lucky mom.  Peyton picked it up immediately with no problems.  He hardly needs incentives and rarely has an accident.  I think he's had three since we've started.  He loves wearing undies and won't pee in them or in a a pull-up.

BUT, and there's always a BUT right?!  He's having a hard time going poop!  All of the above applies to him going poop too, BUT he's having a rough time actually getting it out.  PLEASE HELP!!

He's in major and I mean major pain when he gets the urge.  He's not constipated to my knowledge.  His poop is normal once it does come out.  Sorry if this is TMI, but I'm not gonna sugar coat this one.  :)  Sometimes he'll go a few days without pooping, but I know he has to go and I know every.single.time he gets the urge because he gets a look of horror on his face and yells, "MAMA! POO POO!" and runs to the bathroom.  If we're lucky, we'll spend the next two hours in and out until he goes.  Sometimes it's all day.  Sometimes it goes away until the next day.  But I can't get him to go when he has to go.  It's a huge & painful ordeal.

The worst part is the pain he's in.  The horror look on his face when the urge comes is seriously horrific for me.  He cries and I swear it's comparable to labor, that's how he looks.  And when it gets to that horrible of a stage, I know it's around the corner, but it'll take another hour.  He can't play or do anything during that hour, we sit in the bathroom in tears (yes, me too sometimes).

I've tried fiber to help loosen it and nothing.  I was hoping it was just a new sensation for him, but I'm quickly learning the kid's in real pain.  After it finally does come out, he starts laughing and gets the biggest smile of accomplishment on his face and we're both so relieved it's over!  The pain is immediately gone and so is the fear.

A friend of mine said sometimes they'll get cramps after holding it for so long and maybe that's where the pain is coming from?  I haven't called the peditrition yet, but think I may soon.  Any advice would be great!