Welcome to the forum but I'm sorry you have to deal with uc symptoms like we do.
In your shoes I'd add an immunomodulator like azathioprine/ imuran or 6MP to your biologic as multiple meds are often more effective than just one. Entyvio can take 12-14 weeks to work, so i wouldn't give up on it just yet.
There's no definitive test UC versus Crohn's. A history of colonscopiee and biopsies can help. There's a Prometheus IBD SGI test that's newer and supposed to help. /www.prometheuslabs.com/Products/Default.aspx
Moderator Ulcerative Colitis
John, 38, UC Proctosigmoiditis
Rx: Remicade @5mgs/kg/6wks; 75mgs 6MP, 4.8g Mesalamine DR, and rowasaUC causes complicated relationships with colons :::: we have trust issues ::::