UC Flare - pred not kicked in

Hi,
Any advice please? I was diagnosed with UC 3 years ago, after a month of increasingly BDs and investigating with a flexible stig + colonoscopy confirming UC and I responded well to 2 x 2g pentasa and 1g pentasa suppository for 2 months then advised to go onto "maintenance" dose of 2g pentasa daily. Did that for 3 years, never had a flare, never had any health issues.....fast forward to April this year where I got a stomach bug, started having diarrhoea for 3 days which then triggered a flare that went from 5 BDs a day to 15 BDs in 2 days was sent to A&E by my GP and was given a hydro cortisol drip and a course of steroids, 40mg pred to taper, along with 2 x 2g pentasa and 1g pentasa supos. The blood in the stools disappeared immediately and I went back to "normal" bowel habits quickly, don't get me wrong I had a terrible time on the pred - sweats, anxiety, insomnia, weight gain....just before the end of my course, unrelated to UC I had terrible pains and was admitted to hospital and had a massive ovarian cyst diagnosed and removed by keyhole surgery. I was told to extend my steroids for 1 more week just to cover the "shock" of the op, finished the course and recovered from the op. I had an IBD check up at the end of July, was told my calprotectin score was 67, back to normal was back in remission, and to cut back to 2g Pentasa.
One week later, I felt unwell, slightly flu-ey with stomach cramps and loose bowels, which then went to BD and bad cramps. I put myself back on 2 x 2g pentasa and called the IBD team who told me to carry on with extra Pentasa for 2 weeks. After 1 week I couldn't take it anymore, the cramps were so painful and the BD getting more frequent and bloodier and the GP prescribed 40g pred again. I started on Monday, and have now been on it for 6 doses. Although there was an improvement in less BD per day and less cramping, there is still a lot of blood in the stools and it doesn't feel like the "magic switch off" from flare like last time.
Was I just lucky last time? Was it the combo of the drip and the steroids last time? Can you get resistance to pred? Can you get resistance to Pentasa?
Any advice gratefully received!
I have been on a low res diet since I felt unwell a full weeks ago. I daily take: kefir, probiotics, prebiotics, cod liver oil, vit D, multivitamin. I am otherwise fit and healthy 45 year woman, am a vegetarian. I don't smoke and haven't drunk alcohol since the first flare in April.
Thanks so much

Your case seems very similar to mine. I was diagnosed 4 years ago and also developed ovarian cysts right after diagnosis and became steroid refractive (both Iv and oral stopped working for me). I was hospitalized 3 times and would have 20+ bloody BMs a day. I started remicade and imuran and finally found remission but I would have smaller flares every 3-6 months with blood and mucous.

After seeing an insanely smart and attentive obgyn who was married to a GI she connected my cysts and endometriosis to my ibd. I had a robotic hysterectomy last October and haven't seen blood or mucous since. I have diarrhea about once every 2-3 weeks but literally just once or twice. And my colonoscopy came back 90% healed and my doctors say I'm in full remission.

I Recommend having a consult with a gynecologist specifically one that deals with surgery and endometriosis or cysts.