Your symptoms suggest that you have developed fungal infection
of vagina.also called as yeast infection.
It is normally caused by the fungus candida albicans.
In a healthy vagina,some amount of yeast cells are always present but whenever a person takes heavy dose of antibiotics,the good bacteria called as lactobacillus acidophilus
gets killed and yeast grows in number resulting in itching and white discharge from vagina.
If symptoms are mild,local application of clotrimazole
ointment for 3 to 7 days is enough but if the symptoms are severe or persistent ,you may need oral anti fungal medicine like FLUCANAZOLE for few weeks.It is taken as weekly dose.
Eat more of yoghurt and take lactobacillus acidophilus tablet along with the antibiotics ,you are using.