Be careful about what you eat for the next few days.
The same thing happened to me after my first flush and I was continuing the Master-Cleanse fast.
The cayenne pepper did it to me.
I would suggest gentle foods (apples, plain baked potato, rice...)
Try to avoid dairy, meat and spicy foods.
Your liver just went through something it never has before so treat it gently.
And drink plenty of water.
I hope this helps.