Intermittent fever & Ulcerative Colitis

My wife has a history of ulcerative colitis. After a remission period of over 8 years, she started having diarrhea a couple of months ago and at first we thought it was nothing (we had almost forgotten the UC). This kept progressing until she started getting fever. On a doctor's visit and subsequent bloodwork, a month and a half ago, she was found to be severely anemic due to iron deficiency (haemoglobin just under 7) and the general physician started her on iron supplement, vitamin B12 and Vitamin D (all were low). Her gastroenterologist started her on Mesalamine (4 capsules daily) and later added prednisone 100 mg enemas to try and get the flare-up under control. Things are getting better and she has some of her strength back. There is one puzzling thing that the doctors are not able to pinpoint. This is an intermittent fever that starts in the afternoon and lasts to the night. In the morning the temperature is back to a low 97 degrees fahrenheit and stays stable until afternoon below 98 degrees. Then after that it goes up to 99.5 or even 100 sometimes. She was taking Levaquin initially to see if there was a bacterial infection, but the antibiotic was giving her even higher fevers - once the antibiotic was stopped after two weeks of usage the fevers over 100 degrees also stopped as did some coughing she was having (the doctors say it is rare but maybe her body was reacting to the Levaquin). She also has a headache around the same time as the mild fever and a brain mri revealed acute chronic sinusitis (for which the 2 week course of Levaquin was initially taken) as well as white spots on the mri indicative of migraine. She never had migraine in the past. She is under 35.

CBC's (3 have been taken) show a steady improvement in the haemoglobin (and other factors) though they are still below normal. The doctors say things are moving in the right direction there. Yet the mild fever comes every day in the afternoon. Hematologist says she is not worried about the fever. However, we want this to be explained.

Having read many posts on the internet, there are just too many avenues to pursue. I wanted to see if I could get some help/pointers online. I have researched on infectious diseases and intermittent fevers (malaria etc) but she has not recently visited a part of the world where this is prevalent. Maybe taking the antibiotics has upset her colon bacterial balance and taking probiotics may help.

At the end of the day, I would like for her fever to not come back. Any ideas are greatly appreciated.