So, my two months of sublingual B12 has doubled my level and my MMA is down by two thirds. The doc and I think my deficiency was due to a different type of malabsorption and/or an effect of a primary immune deficiency I was diagnosed with in the fall of 2016 after a year of near constant diarrhea. The dietary choices I made weren't so great during that time.
Once I started to do FODMAP as best I could, and added kefir to my diet, my gut has been much improved. Still can't eat much in the way of raw veg. No longer having diarrhea unless I eat salads. Weird, i know. Traditional Tibetan medicine practitioner told me never to eat or drink cold stuff and to make sure veg was cooked until soft, not al dente. It seems to all help.
Thank you all for your advice while we sorted this.