You may actually have grounds for a discrimination lawsuit there Ron. If she's telling you that you've been "causing a disruption" for two years, but the higher ups say no, you haven't, then she's obviously gunning for you in particular with the dress code. Maybe drop a hint to the higher ups that if this woman goes ahead with forcing you into trousers you'll look into hiring a lawyer?

Disclaimer: I'm not a lawyer, I've never played one on TV. OK, I played a judge in a high school play once, but that doesn't give me any legal expertise, you know.