most probably is infection,
this needs treatment by either oral drugs or vaginal drugs.
go and see the doctor to see what happen.
my family doctor in Tai Wai (Dr. Ho) is quite good on this and he can tell you what happen (because i have seen him 1 months ago for the same problem),
he is very nice and may be you can see him if he can help you.
His clinic Tel no 2634 5530