What could cause vaginal burning with milky discharge that appears to have tiny pieces of skin in it? Been tested for STD, BV, and Thrush. All negative

Vaginal discharge. Possibilities include chlamydia, trichomonas, BV, gonorrhea, yeast- note it appears you were tested for those . May also get strep mycoplasma, ureoplasma ( they tend to live in vagina but may get overgrowth) . Recheck for yeast and then would consider empiric treatment with azithromycin if not allergic as will cover, GC, chlamydia. strep, myo .ureo . Flagyl will BV and Tric f/u /w/ gyn.