I think your symptoms are quite normal and I put it down to withdrawal from your normal foods rather than detox.
I have had those symptoms a few times, always in the first 3-4 days, but then it goes away. On my last urine fast I massaged myself with urine and it was much easier.
John Armstrong (The Water of Life) said to consume all of the urine you pass, massage your skin with some (obviously some of the urine you pass) for a couple of hours a day, sip cold water too, rest as much as you can and fast for 7, 14, 21, 30, 45 or 60 days depending on how severe your health problem.
I felt like I was going to drown and my stomach would burst when I tried drinking it all so I drank most of my urine on the fast. I liked the old urine for massaging - save a wine bottle full a week before and keep it with a tissue or open weave cloth on top to let the ammonia evaporate. I still do this now, sit in the bath, use a small dipper into half a glass of old urine, the dipper is like a thimble, pour a little into my hand and massage areas with it until the skin is almost dry. Then I shower only using soap around my crotch. It takes me about 20 mins and I use about 1/3 of a cup each time.
You still have food in your system until about 48-72hrs so the best healing occurs after that. Another thing I do occasionally is hold a mouthful of fresh morning urine while I massage. I once read from an Indian urine healer that if you do that for 15mins a couple of times a day you will never suffer mouth, gum or teeth problems.
I would advise you to give up alcohol, Sugar (sweet) foods, and coffee (caffiene) two weeks before your fast and try to go vegetarian for two days before your fast. I do not smoke anymore, gave it up 30 years ago, but I have been told that the withdrawal symptoms of nicotine lasts for two years! Giving up early helps to reduce the symptoms you describe. Then I would fast for a min. of 7 days. If you massage daily you should find that you have quite good energy while fasting, even if it is not able to sustain you doing heavy work. At lower levels like walking around the house, doing light duties, etc. you should have plenty of energy, but those first 72 hrs are the worst.
Three fasts ago I gave up coffee etc. two weeks before and the first week was much worse than the beginning of the fast! Now I do not have coffee at all, I am much better off without it. Some people do not realise that foods can have caffiene, like pop (soft drinks). I think you should be prepared to rest a lot for the first 2-3 days.