Three months of abnormal discharge with no answers

Seeing if anyone has experienced this or has any answers. For three months I have had thick, yellow discharge. It causes irritation and itchiness. I assumed it was a yeast infection. I went to the gyno and she said it was a yeast infection. Two Diflucan and 10 days later, still having symptoms. Went back in and saw another doctor, she looked under the microscope and didn't have any answers. It only showed high leukocytes. She prescribed a week of doxycycline, no improvement. Did another week of doxycycline, no improvement. Came back and saw another gyno, she tested everything (cultures, pH). Everything negative, cultures only show high growth of normal flora. Prescribed two weeks of clindamycin and hydrocortisone suppositories to place nightly for two weeks. During this time, the discharge greatly improved. Once I stopped using it, the discharge came back. The discharge is now darker yellowish-green and very thick (like when you blow your nose and it's dark yellow-sorry TMI). I'm at my whits end! I can't stand this anymore. She says to try two more weeks of hydrocortisone suppositories. Any gynecologists that can weigh in or seen this before?