You felt sick and yucky because your body had released all those terrible toxins. As the stones are passing through your body, they are making one final misery call to your body producing all those sick feelings you were having. But, guess what! They lost their battle and you are winning the war!
As you complete your cleanses, (and I hope this won't be your only one) you will notice that each cleanse will be different. I didn't pass those dark (I like to think of them as old) stones until my third liver cleanse. Toward the end of my cleanses, (8 total) there would be less and less until there were none.