Sounds like you were heading into detox and stopped the process by eating. Most likely that's what happened. At this point I'd simply recommend that you start eating only raw fruits and veggies for a few days to stimulate the digestive system again. That should solve your constipation, as well as help the body to get rid of whatever it was trying to get rid of when you stopped.
The thing to remember when fasting is that food will NOT help you feel better. Fasting crises are times when the body is trying to get rid of junk, and in the beginning of any fast, lots of toxins are being released quickly into the system which can cause a myriad of symptoms (headaches, stomach aches/cramping, fuzzy-headedness, joint achiness, even cold/flu-like symptoms). These are normal and are best dealt with using good elimination techniques (like the SWF (Salt-Water-Flush) or an enema) and drinking lots of lemonade and extra water.
Fasting takes time and a commitment to walk through the hard stuff. If you decide to try another fast, I recommend you browse the forum and read the post Pepe put up on detox symptoms. Only you can decide if your lifestyle can handle the symptoms associated with cleansing. Meanwhile, much cleansing can take place by simply eliminating things like yeast, white flour, caffeine, and refined sugars. An increase in fresh fruits and veggies is always a good idea.
I'm also posting another great site on juice fasting below. There is so much information on healthy eating on that website that it will blow you away!