Don' t worry its normal and happen with girls.
To get rid of this problem
1. Never wear tight panty and pants.
2. Allways wear cotton wnderwears and during periods keep cleanness.
3. Keep your viginal area dry and clean.
4. Never use harsh soaps at your viginal area.
5. When you go to toilet and for urinepass after that wash your viginal are with fresh water every time.
6. Instead of using hair remover cream use shaving blade for hair removing.
7. Never use oil or mositure creams in your vigina.
8. At night wear lose under garments.