I Have A Vaginal Discharge That Apparently Dries To A

I have a vaginal discharge that apparently dries to a yellowish green. If I take a q-tip and swab my vagina, there is only a cloudy white discharge, but if I wear a pant liner for a few hours I will have that yellowish green discharge on it. There is no odor. It has been going on for months. I called my doctor and he gave me antibiotic for bacterial vaginitis. When it was still there after the antibiotic was gone, I went in to the office. He swabbed my vagina and said it was just residual from the infection, but it never went away. Any ideas?