I have an unusual odor when I urinate. What could that be?

Lots of things. Some common ones are infection and your diet. Certain vegetables, especially, can cause an odor. Asparagus is a common culprit. Get a doctor to test your urine for causes.
High protein. Bad smell in urine is a combination of high ammonia and high protein - if your urine foams while peeing it is high protein. So need to drink more water roughly 1/2 body weight in pounds as oz of water. If it is high ammonia body is extremely acidic need aloe drink and vit d in addition.