I get a come and go fever with my flares; same as you they're usually in the evening when symptoms are worst. I read that a slight fever is a sign of inflammation somewhere in your body and will sometimes occur with UC. I take acetaminophen but I make sure it comes down with one dose (that's I'm not continuously on it) and it's not too high. A former GI said taking steroids can mask an infection so if you have fever you want to tell your GI; I notice you’re taking a steroid enema. Hope you get better soon.