diuretics, ADD/
ADHD medication, coffee, alcohol, dark red foods and fruit juices, such as beets, cranberries, etc.).
I would reflect on your recent dietary patterns, if I were you; and would try to determine whether you've been consuming anything consistently enough to cause a color change.
Also, what did your renal doctor check? Did s/he only check kidney function (GFR type tests), or did s/he also examine the state of other organs involved in eliminating urine from the body?