I sympathise - I don't like meds either but avoiding them while in a flare is not going to help - as others have already said.
I would at this point be asking for a flexible sigmoidoscopy to see how far up the colon this has travelled, and a further colonoscopy if necessary. Also CRP and ESR blood tests to see how inflammation markers are doing.
The protocol now from the team I am with, for those who can tolerate mesalazine, is to take a high dose of Mesalasine, both oral and rectal until the inflammation subsides (though if your inflammation is only rectal, you may not need oral). With steroids as next line of treatment if mesalazine alone not enough. Previously I used to get put straight onto a steroid enema. The mesalazine does seem to get it under control for me. Once there is no blood and CRP and ESR are back in range, I reduce to a low maintenance dose of mesalazine.
If your liver and kidney function are monitored through regular blood tests, you don't need to worry further about
mesalazine side effects. Don't forget that mesalazine is derived from salicylic acid, which is a chemical copy of willow bark, used by humans for thousands of years for pain and inflammation, so it is not the worst chemical out there. Some people are sensitive to or ever allergic to salicylates but doesn't sound like you are.
It would be incredibly rare to control UC through diet alone. The other thing that it sounds like would help you is looking at ways to relieve your emotional stress. Stress hormones do seem to affect UC for many, I suspect that the chemical changes they cause produce a good environment for the aggressive bacteria to proliferate.
If you have a spare couple of hours, watching this video as a start to learn about
a technique called mindfulness would not be a wasted couple of hours I'd say.
www.youtube.com/watch?v=_If4a-gHg_IThere are a lot of other meds too but I have never had to go on any of them.