i have had the same treatment as your brother. The steroids did eventually calm that particular flare up , but I was quite ill as well. I get recurring bouts of it from time to time, most recently a couple of weeks ago.
I've had it on and off for about 4 years. the first bout , I lost a stone in 10 days, then it was failry mild for a while, then it came back again, and it took about 6m for it to calm down again,after more steroids and increasing my mesalazine. At the moment I have only mild symptoms of it, which makes it bearable, but it can make me feel dreadful tbh, and I have lost more weight.
I was told by the consultant that there was no real link to avoiding certain foods, but when you are having a flare up, fruit and veg are likely to aggravate it more. There is also a familial link, and in my case this is the case, as both my sister and my brother have had similar symptoms in the past.
Meds I take are Mesalazine (asacol), everyday, steroids when needed for bad flare ups, and sometimes, as the mesalazine can make you feel nauseous, esp if like me i have recently upped my dosage, I take an anti sickness drug.
It can make you feel really bloody awful, colitis, but when it has stabilised, hopefully he will go into remission for a long time, and will start to feel better. Once the inflammation in the bowel has been calmed, he should find himself returning to normal.
Hth.