I have a lot of stomach problems when I exercise, expecially reflux. Since you are riding in the a.m., the problem may not be the food in your stomach, but an empty stomach - the nausea especially makes me suspect that. I have absolutely no medical expertise but here are some ideas that popped into my head immediately:
-I take an H-2 blocker (Zantac, Pepcid - I take generic Zantac a.k.a. ranitidine) with water as soon as I wake up, and it makes a big difference. If I forget it and exercise in the a.m. my stomach can definitely rebel. It may take a few days of this routine for your body to adjust to this.
-get some bland, absorptive food in your stomach well before your ride - such as white bread. Not a lot, just a little something to take the edge off, absorb any excess acid in your stomach.
-taking a multivitamin on an empty stomach can make me feel the way you describe - are you popping vitamins or supplements before you exercise? If you are, when your blood starts pumping there may be a rush of vitamins/chemicals into the bloodstream that causes you to get nauseated.
-go to the doctor. Your symptoms sound kind of extreme and a doctor might want to prescribe something, or investigate whether there is some physiological problem that is making your stomach roil and boil when you exercise. You shouldn't have to live with this.