colic before endurance ride ?

["Lisa" <lpopp@pa.net>]

Hi campers,

I'm counting on your experience and expertise to help me make a tough decision.  I was planning to do the No Frills 25 ride this Sunday, my first endurance ride with my own horse.  I was riding Razz yesterday, when 2 miles from home he started acting colicky.  I managed to get him home (it wasn't easy) and give him 9cc of Banamine and he seemed to come around.  The whole time he was in distress he was looking st his right side and wanting to lie down, but still oddly wanting to nibble at grass.  After dinner I went out to check on him and he was in trouble again.....more Banamine...and he seemed to come out of it.  He has been fine all day, a little tired, but eating, drinking, pooping, etc., normally.  I gave him 1/3 of his usual ration tonight, and hay.  I believe what caused this colic is too much lush spring grass.  I have only had him 3 weeks and the place he came from had NO pasture.  I thoughtlessly let him out in the yard to graze for an hour and a half Sunday evening, and then let him out on pasture a little again Monday morning.  Monday afternoon was when he colicked.
My question is, would you take this horse on a ride 6 days after a colic like this?  I have really been looking forward to this ride and if he is ok, want to do it.  I would appreciate any input, I do not want to hurt this horse.....he is my first priority.
As an aside, I tried in vain to get a vet out here to look at him.  My local vet said that there was nothing he could do that I hadn't already done (read: didn't want to come) plus a bunch of other crap that I'll spare you.  I called another and left a message on her beeper, she hasn't returned my call.  I called the local equine hospital and got the fax machine.  It was a rough night....
I am a little behind on my digests because of being so involved with this horse, so I would appreciate it if you could post to me directly.  Any and all suggestions and advice appreciated.  I have the utmost respect for you all.  Thanks,
Lisa <lpopp@pa.net>