Sorry to hear that you are experiencing all the symptoms you describe and the terrible depression. Your history of eating and exercising is not known to me so it is rather difficult to nail down the symptoms and why?
However, first, dark urine. The first thought comes to me is that it must be detox. Also if the urine is dark brown, you may should get it checked right away to see if it not blood in the urine.
Water is great to drink in this condition. Also try to just eat Watermelon and nothing else.
Since I do not know what you eat, try to eat as much raw foods you can, no processed and no cooked foods. If you do one month of raw foods, depression will go away. Drink freshly squeezed juices.
When you feel better do a Liver Flush or go on water fast.
I hope you feel better soon. You are the only one who can help yourself. But keep posting here with a daily dairy of what you eat and how you feel.