My girlfriend is 23 and has a odor in her vagina could this come from her seriousis treatment?

Possibly: I'm not quite sure what treatment you are referring to. Procedures that are associated with vaginal bleeding (like a d&c) can sometimes have an odor of the remaining blood but, odors can also be associated with infection and should be evaluated by your doctor.

Agree with Dr. L: Once she has completed the treatment, re-evaluate. Stay away from douches as these can only make matters worse. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.