Mesalamine (as in Asacol in US) didn't work for me and I was switched to Balsalazide which IMO didn't do anything either. I still take Balsal. but diet modification is the reason for my remission plus probiotics (VSL#3) and lately wild oil of oregano ("woo" on this forum) and wormwood extract have been beneficial too. One is antifungal and woo is natural antibiotic I think.
I know this is not what you want to hear but can only say what worked for me.
I could probably stop Balsal. but too superstitious.
BTW have you tried mesalamine enemas. Now they do work for me.
I have tried all the things you mentioned. Mesalamine enemas don't seem to work for me but I always neglect taking them.