Some people who are prone to thrush are advised against using anything fragrenced, bubble bath etc, but I wouldn't worry too much about a bit of shampoo
Found this: "Thrush is not due to poor hygiene. However, the normal conditions of the vagina may be altered by excess washing and douching of the vagina, bubble baths, scented soaps, spermicides, etc. The normal mucus and bacteria in the vagina may be upset by these things and allow Candida to infect. Therefore, it may be best to wash just with water and unscented soap, and do not douche the vagina."
here:
http://www.patient.co.uk/showdoc/27000589/