Hi,
Welcome to the ehealthforum and I am glad to help you out. There are a number of causes of vaginal itching and the final diagnosis is possible only after doing a physical examination and maybe doing some investigations.
Chemical irritants like contraceptive foams & jellies or any vaginal creams can cause vaginal itching. Vaginal candidiasis (yeast infection) or vaginitis due to any cause can cause itching. Sexually transmitted diseases like herpes or chlamydia are one of the commonest causes of vaginitis.
The scratching should be avoided as it usually tends to worsen the problem. Any sexual activity should be delayed until complete healing takes place and condoms should be used in case sexually transmitted disease is suspected as an underlying cause.
I sincerely hope this information helps. Take care.