Colonoscopy meds keep making me puke, HELP!?

I know this is gross but I have to have a colonoscopy tomorrow first thing in the morning but I can't keep down the stuff that cleans you bowels. Its a liquid that you're supposed to drink and to me it has no taste. It smells nasty but I put in a flavor packet that mask the smell pretty well for me. So I'm sure I'm not puking it up cause of the gross factor cause to me taste and smell are no problem. I just drink it down and everything seems fine but in like 2 mins I can't stop from throwing it all back up. Its Sunday so I can't get in touch with any of my doctors and I have no idea what to do now. This appointment tomorrow is extremely important cause I'm only 26 and I've been crapping up alot of blood and I'd really like to know why. Has anybody been through this before? What am I supposed to do if the stuff won't stay down?