I agree with getting an Rx for mesalamine enemas and also agree with keeping a food diary and begin figuring out what foods could be a problem. You already know about
broccoli :-(
Eliminating dairy and gluten would be a good first step since these are common offenders for UC'ers. Try it for 2 weeks and if you have some success (it may not be total success just improvement) then you can expand your search for other problems. Everyone seems to to slightly different in their food intolerances so you really need the food diary to determine yours.
No your doctor will not support diet modification (very rarely) but that's OK.
People here use all types of probiotics so find one that works for you. Yes VSL#3 is expensive but that is due to how many million/billions of live probiotics it has. Cheaper probiotics have fewer so you have to use more and ends up being just as expensive.
Good luck. It does get better