I think most doctors know very little about B12 or its affects, I know after I was diagnosed and had a bad reaction to the injection my doctor did some reading about it on the internet and rang my endocrinologist to find out more. I got most of my information from the net and other people with the same disorder. The first couple of injections I had made me feel quite ill, my doctor wasn't aware that people could be sensitive and tried to laugh it off until I broke out in hives after every injection! After talking to a few people about it I sort of settled myself to the idea that the first 5 injections were the worst and after that most people start to feel better (and their skin clears up etc)Hopefully the pills won't cause you such a rotten reaction as the injection did.
Have you had an intrinsic factor test? I read your post on your diet and it didn't seem so bad, so I would be a bit worried about your absorption. If you have had an intrinsic factor test and it was normal I would start taking a multi-vitamin daily with B12 included in it to try and keep your level up so as to avoid another B12 'crash'.
I hope you are feeling MUCH better soon
All the best!