Yes, constipation is a common occurence after one has quit smoking. Nicotine is a stimulant and, as a colon hydrotherapist, I would hear many 'quiters' complain about constipation after they kicked the habit. The breaking out is probably related to the constipation, and also your body'd way of eliminating the toxins that have built up in your system while smoking.
Make sure that you drink plenty of water, get plenty of fiber in your diet, exercise...and you can also use a bit of Epsom Salts to keep things moving (but not so much that you get diarrhea). You can also use colonics or enemas to assist with flushing the toxins out of your system faster. As your body chemistry adjusts to the lack of nicotine you should become more regular again...provided that you are eating right, well-hydrated and excercising.