I would think your reaction are caused by the body ebginning to cleanse from getting a DECENT food source for a change. Yes the cleanisjng/detox would begin pretty soon depending on your toxic load, how long you have been abusing your body on cooked/acid/ & mucuss forming foods.
All depends on where you are and what you have been doing to your body uptill now.
What you should be more concerned about is the LOADS of mucus being formed in your gut because of eating poor food choices/poor food combining. This one doesnt see or know about untill too late.
FRUITS/nuts/seeds, and RAw Leafy vegis' will not do this to you. (Ie Mucusless foods) Sadly pizza does not fall in this realm lol.
I would strongly recommend reading a book called Mucusless Diet to get a understanding on the true nature of Mucus in relation to our foods.
You may also want to investigate a herbal formulae by Dr Christopher orginally called the Lower bowel Balance formulae. This is a non invasive method to remove mucus from the intestinal tract, when used with a mucussless diet. When all of that is being cleaned you will fidn you juicing much more effective. Oh yes, whilst cleaning that out, you may as well use a GOOD deworming formulae at thge same time, kinda kill two birds with one stone.
Lapis makes a very good point. You will get plenty bang for the buck learning about food combinations and POOR food combinations, such as mixing fruits with ANYTHING else, or mixing proteins with carbs etc etc. These two are good example of poor food combining.
Kinda makes sense to go to the CAUSE and work up, rather than use plasters because they feel/ taste nice.