My 6 month old daughter has foul odor coming from her urine.... her vagina also smells fishy. the urine smells like ammonia.. she only drinks milk?

Maybe an infection: You should take her to the pediatrician to make sure she doesn't have an urinary tract infection.

Possible UTI: This is frequently the only symptom of a urinary infection in babies so you need to get a urinalysis done. Her pediatrician or her/his nurse can apply a urine bag. Will need a catheterized or supra-pubic specimen for culture if positive. On the other hand, but less likely, smell might be from uninfected urine or vagina if she inadvertently pushed a little stool or something else up her vagina.