After my first bike commute two weeks ago, I felt completely sick and wasn't able to eat anything for several hours later. I had eaten two small muffins beforehand and drank a mixture of 1/2 gatorade, 1/2 water.

Yesterday when I biked to work I was starving and easily wolfed down some cereal. This time I didn't eat before I left, and I rode strong (it takes 70 minutes).

How much are you eating beforehand? Perhaps this is what is making you sick. You might need to eat less or to allow more time after eating beforehand and riding.