Greenish vaginal discharge with severe itching points to a diagnosis of:

Patients infected with Trichomonas vaginalis presents with pruritus, dysuria, dyspareunia, or abdominal pain. Vaginal examination in these patients copious frothy, yellow or greenish discharge. There is also inflammation of vaginal wall and cervix with punctate hemorrhages. Wet mount examination of the discharge shows motile organisms. Rapid antigen and nucleic acid amplification tests are highly specific and much more sensitive than wet mounts. Metronidazole or tinidazole is the treatment of choice. Ref: Rosenthal P.J. (2013). Chapter 35. Protozoal & Helminthic Infections. In M.A. Papadakis, S.J. McPhee, M.W. Rabow, T.G. Berger (Eds), CURRENT Medical Diagnosis & Treatment 2014.