Wow, that's great that you got a juicer and started changing what you eat. A lot of people can't fast one day, never mind five. I'd say that the longer you can fast and feel ok and not lose too much weight, the better, but you have to go with what you feel is best for you. I usually juice fast for 10 to 20 days.
All the energy that went into digestion can now go into healing, detoxing and regeneration. If your elimination channels are blocked, you won't feel so good. There are herbs that can help move the toxins that are stirred up by fasting out of your body.
Whatever health problems you have probably took years to develop and will take time to improve. So don't be discouraged!