Leon,
I agree with probiotic. Many people actually are intolerant of the mesalamines and don't know it, and get UC like symptoms which they mistake for UC.
There have been many on this forum, myself included, who have done very well with a combination of: diet modification (gluten and dairy free), adding certain supplements like slippery elm powder, l-glutamine for colonic repair, ensuring adequate levels of vitamin d3, adding omega 3's, probiotics are definitely key, and you could also look into LDN, low dose naltrexone. Once you get the LDN script, it only costs about $30. a month, and LDN has almost no side effects.
There are things IMO that you can control, which will have a direct impact on your disease, the symptoms you experience and their severity.
I was able to control my UC into remission through various supplements, probiotics, diet modification, and LDN , low dose naltrexone.
For more info on the protocol which has put me into remission, please go to this link: https://www.healingwell.com/community/default.aspx?f=38&m=1666318 , and look at the 11th post.
I hope you feel better and let us know how we can help you.