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.