most common cause for abnormal vaginal odor and discharge.
1. tampon that has been forgotten - this can be serious and if this is the case you need to remove it and call your doctor.
2. vaginal infections - those that are associated with odor are bacterial vaginosis, trichomonas and to a lesser degree yeast infection.
yellow/frothy discharge suggests bacterial vaginosis or trichomonas.
white/chunky suggest yeast.
Unfortunately I cannot make a determination online without doing an exam so you'll have to see your doctor. Each of the infection listed will require medicine to resolve, such as an antibiotic for instance.
Hope this helps,