Hi,
Welcome to healthcaremagic.
The yellowish green discharge is typically seen in infection with Trichomonas.The delay in periods could be due to
hormonal imbalance when
pregnancy ruled out.
Also hormonal imbalance can cause vagina and cervical mucosa prone to infections which explains the problem in you.
Do visit a gynaecologist who after examining you can confirm the fact and treat you accordingly.
Wish you good health.