Howdy, sorry to hear that your disease has continued to progress. You should absolutely get a second opinion (make sure the next doctor can view your MRI and any other tests you have done), but from what you have posted so far, it seems you have a pretty typical case of IBD.

Basically if you do not treat it, the disease is likely to keep progressing and destroy more healthy tissue, at some point surgery will be the only option, but at your relatively advanced age might not be something you bounce back from. Also, feel free to browse this forum for people with "horror" stories from relatively "routine" bowel surgeries - I am one of them. Not that surgery should be discounted, but I feel that gastro's are a little too gungho about sending people under the knife.

If I were you I would ask for prednisone (~40mg-ish tapering down for like 2 months) to get the current flare under control, meanwhile starting on Remicade or Humira (these are essentially the same drug, do your research but Remicade you get an infusion every 8 weeks, Humira you inject yourself every 2 weeks) to maintain remission. These drugs are not perfect but they sure beat suffering unnecessarily. After about 6 months if your symptoms are not under control your doctor needs to evaluate whether the remicade/humira are doing their jobs (a couple of $100 blood tests, hope you saved up $$$), if not, it's time for prednisone + trying a new drug. Rinse and repeat until you get a few years of symptom free life. Good luck.