Also, I had posted once before about how important it is to get to the root cause of the deficiency. My primary said there's no need to but I am thinking about calling the gastro doc anyway. Thoughts?
Of course it's very important to find out the cause. Vitamin B12 deficiency causes all sorts of physical problems, sometimes permant. You can't keep taking more and more huge quantities of vitamins for the rest of your life without a good reason.
Some thoughts. (I'm certainly no expert and this is just to get the discussion started)
Too much Vitamin B1 can create a deficit of B12.
Celiac (gluten intolerance) can damage the intestines and make it difficult for your body to absorb nutrients. In fact, if you have damaged intestines from celiac, then it may be that taking vitamin b12 orally won't help, unless it really is being absorbed in the mouth (see how ignorant I am?) It's something to look into.
There are of course all sorts of other reasons why someone may become so deficient in a particular nutrient that they have to take massive dosages to get back on track. Unless you find out the underlying reason, there's no way of knowing whether you've "cured" the situation by taking high dosages now -- there's no way of knowing if the deficiency will return or not.
My suggestion is to insist (loudly) on being referred to a gastro doc, or if your insurance allows it, making an appointment yourself.
I'm glad you're starting to feel better. Let us know what you find out.