What Causes Cut On Outer Vaginal Area?

Hi I have this paper cut like on the outside of my vaginal area! I did have trichamonias but I just took my last two pills today and done with the meds! Am I cured now or where is the cut coming from? It burns when I touch or wipe it and it just showed up today! I haven t had sex or anything since taking the meds for seven days and it just showed up and started hurting today!