FWIW, our docs here do not rx D2 anymore, given that D3 is over the counter and (and I quote) "as good, if not better" than D2. Typically, you buy a very cheap product at our pharmacies that has 4 oily capsules with 25,000IU of D3, and you typically take one a week. If you are very low, you can safely take 2 (i.e. 50,000IU) the first week. (I did this a few years ago, with obviously no ill effects).

My doc now routinely advises many of her patients to get this product during winter, as a vast percentage has a deficiency or is borderline. Also, this D3 product (D-Cure) is so common and ingrained that there's just no reason to go the D2 route.

Personally, I prefer to take a daily dose of 4,000IU (D3 ). It comes down to the same dose, and I have no proof, but I suspect that works better than a large dose every week (how much of that would be absorbed?)

I have however stopped taking it back in May to see if I could get my levels up by being outside most of the day. Will be interesting to have it tested/see the results in Sept.

On a more general note (and this is not a dig): please read this forum carefully. There is so much info on D3, B12, magnesium, B1 etc. that it's almost impossible to miss. All these can be bought cheaply and taken safely. They may not cure PN (in this case) - although they sometimes do (!) - but they are so fundamental that healing is almost impossible if you don't have these levels in a safe and comfortable range.