I used Daktarin on my little one from 12 weeks old after many failed attempts with Nilstat.. I found Nilstat did nothing for my baby and it was awfully messy and sticky.. yes, the pharmacy will give you a very hard time about getting Daktarin however if you are sensible you will be fine. Just make sure that you spread the gel well over your finger first then spread in your babies mouth. you will be fine and the thrush will almost disappear on you - Daktarin works wonders, for me Nilstat did nothing at all..
Good luck